718 GT4/Spyder/GTS 4.0 Exhaust OAP (OPF/GPF delete) - Page 2 - Boxster/Cayman - PistonHeads UK

Has anyone on here fitted a set of OAPs to their GT4/Spyder/GTS 4.0? I've seen clips of the Akrapovic ones and really like the sound of them, so thinking about potentially getting them in the future to go with the stock manifold and rear section, with potential of adding a rear section further down the line. For anyone that has done it, does it make the car drone at all? Does it make it that much louder that you could get in trouble on track days? Also, do you have to get the car remapped to have them installed, or can you install them without a remap? If anyone has any knowledge of how it affects warranty as well that would be great to know. I assume it voids warranty, but I was speaking to someone who has a system fitted on their GT4 (OAPs and Back box), and when it went back to the dealer for some work, they passed it for warranty work even with all the exhaust parts he had on it. - I will ask my dealer about this, but interested to hear peoples opinions

I have a replacement rear silencer, with the standard headers and OAPs. I have not gone down the replacement OAPs route because: 1. You'll need to remap the engine. Without the sensored GPFs the exhaust is much freer flowing and you'll need to adjust the fuelling to match. 2. It probably makes the car illegal on UK roads. Removing emission control equipment will mean the car will fail an MOT. Insurers won't be too happy either I suspect. 3. Warranty isn't an on/off switch, it depends which part you claim for and whether the mods caused the problem. If your engine goes pop I suspect Porsche won't replace it if you've changed key exhaust parts. 4. If you remap the car it most likely means it can never again go into the OPC network as it will fail any diagnostic checks. If you're happy with that then great, but I reckon you'll find most people haven't done this kind of thing to a nearly new 70k+ car under the factory warranty. Any change to the exhaust system will bring in drone in my experience. The standard system is very clever and drops volume levels at the correct engine speeds by closing the exhaust valves and routing the gases through a very heavily silenced section, opening them again as the revs go above the "drone zone" to a straight through path. Removing the GPFs or adding a freer flowing silencer will bring the levels up and bring in unwanted resonance in the 2k-3k rev area. For track days, my car blows the same volume as a standard car at 4k revs (~90dB) because it still has the GPFs fitted. WIthout them the car will be louder for sure as at 4k the only silencing will be coming from the catalytic converters in the headers. I have had warranty work done on my car after being fitted with a replacement silencer, but I haven't claimed for anything engine related. I'm under no illusions that if I have an engine problem that it potentially won't be covered. Probably not the answers you wanted, but I hope that helps Edited by Twinfan on Friday 20th May 09:11

Twinfan said: I have a replacement rear silencer, with the standard headers and OAPs. I have not gone down the replacement OAPs route because: 1. You'll need to remap the engine. Without the sensored GPFs the exhaust is much freer flowing and you'll need to adjust the fuelling to match. 2. It probably makes the car illegal on UK roads. Removing emission control equipment will mean the car will fail an MOT. Insurers won't be too happy either I suspect. 3. Warranty isn't an on/off switch, it depends which part you claim for and whether the mods caused the problem. If your engine goes pop I suspect Porsche won't replace it if you've changed key exhaust parts. 4. If you remap the car it most likely means it can never again go into the OPC network as it will fail any diagnostic checks. If you're happy with that then great, but I reckon you'll find most people haven't done this kind of thing to a nearly new 70k+ car under the factory warranty. Any change to the exhaust system will bring in drone in my experience. The standard system is very clever and drops volume levels at the correct engine speeds by closing the exhaust valves and routing the gases through a very heavily silenced section, opening them again as the revs go above the "drone zone" to a straight through path. Removing the GPFs or adding a freer flowing silencer will bring the levels up and bring in unwanted resonance in the 2k-3k rev area. For track days, my car blows the same volume as a standard car at 4k revs (~90dB) because it still has the GPFs fitted. WIthout them the car will be louder for sure as at 4k the only silencing will be coming from the catalytic converters in the headers. I have had warranty work done on my car after being fitted with a replacement silencer, but I haven't claimed for anything engine related. I'm under no illusions that if I have an engine problem that it potentially won't be covered. Probably not the answers you wanted, but I hope that helps Edited by Twinfan on Friday 20th May 09:11 Many thanks for the info Twinfan, this is my first car with one of the OPF filters so not entirely sure how modding them works. Nothing set in stone yet, was just a thought I was having, but seems like its more trouble than its worth! I don't really want to tune the car to be honest, so looks like OAPs are off the table... Liked the idea as was a lot "cheaper" than the many back box systems available, but looks like I'll just have to save harder for a back box system and stop being a cheap skate!

They're cheaper because they're just straight pieces of pipe, obviously the silencers are faily complicated due to the route they have to take. There don't seem to be that many cars kicking around with difference silencers, even though there are several options available. JCR seems to be most popular and arguably the best because they claim it's drone-free, but I haven't had chance to hear one in person to know for sure. Every other option out there drones to a certain extent so I'm a little sceptical of the claim. That's just me though! The standard system is very well designed and does an excellent job. The thing to remember is that it is what it is, and you can't make it sound like the older cars...

Quite a few people are doing this now. There are solutions for CEL without remapping with the use of a plug-in ODB2 Code Blocker, that doesn't cost that much, and obviously conveniently reversible... so remap isn't the only route. All the solutions have a element of drone... its just a question go how tolerant you are, how you perceive it, and how much of the rev range it occurs for...

TDT said: Quite a few people are doing this now. There are solutions for CEL without remapping with the use of a plug-in ODB2 Code Blocker, that doesn't cost that much, and obviously conveniently reversible... so remap isn't the only route. Not sure I'd be happy just blocking the sensor signal if that's what they do? Yes the car will run without warning lights, but it can't be good for engine longevity. However, that's probably not on the minds of a lot of people if they only plan on having the car for a couple of years.

Twinfan said: TDT said: Quite a few people are doing this now. There are solutions for CEL without remapping with the use of a plug-in ODB2 Code Blocker, that doesn't cost that much, and obviously conveniently reversible... so remap isn't the only route. Not sure I'd be happy just blocking the sensor signal if that's what they do? Yes the car will run without warning lights, but it can't be good for engine longevity. However, that's probably not on the minds of a lot of people if they only plan on having the car for a couple of years. Who really knows. ... Just highlighting that there is another way, and people are doing it.

Oh, indeed. Cheers for the info T

TDT said: Quite a few people are doing this now. There are solutions for CEL without remapping with the use of a plug-in ODB2 Code Blocker, that doesn't cost that much, and obviously conveniently reversible... so remap isn't the only route. All the solutions have a element of drone... its just a question go how tolerant you are, how you perceive it, and how much of the rev range it occurs for... Thanks for bringing this one up TDT. If the dealer was to ever plug the car into a computer, any idea if they can tell if the code had been previously blocked off once removed and put back to standard with code blocker removed?

I'm no stranger to mapping cars, done a few OEM and standalone ECUs (mainly rotary), although I'm not sure how the OBD blocker works to be honest, I'm assuming it blocks all DTCs from the ECU? And not just the ones relating to the OAP which could be problematic if you have other serious problems occur. I've heard on good authority that the ECU actually pulls timing out of the engine even when running 98 octane fuel if you have GPFs, and actually running without them means the ECU does not do this. For anyone that doesn't know, the ECU will only pull timing if it detects knock over a predetermined level within any of the cylinders, so I think running without the GPFs is actually a good thing for the car/engine and well within the capabilities of any modern ECU to adjust for the excess flow through LTFT's and STFT's. The cars inflow is metered through a Mass Air Flow meter so notwithstanding tolerances in the sensors the fueling should always be correct for mild modifications such as this.

Carl9729 said: I'm no stranger to mapping cars, done a few OEM and standalone ECUs (mainly rotary), although I'm not sure how the OBD blocker works to be honest, I'm assuming it blocks all DTCs from the ECU? And not just the ones relating to the OAP which could be problematic if you have other serious problems occur. I think this is correct or at least it needs to be 'trained' on what to block. A few people i know have run this... available from D911... but then initially some functions like Cruise Control stopped working - once historical codes were removed... all works as intended. Edited by TDT on Wednesday 14th September 18:15

Is anyone here actually using this OBD solution? Any other issues besides cruise control not working?

Bump, curious on the above too

I'm still interested also! Really want the Akrapovic ones, might just go for them and see what happens...

The Akra certainly sounds great in the video, but do you really want to drive a car that is no longer road legal and invalid insurance for the sake of some aural stimulation?

Did anyone go this route in the end?

I'd also be interested in hearing from UK guys going this route

Is it possible to ditch the GFP without a remap?

I never ended up going down this route in the end, did talk to some garages about doing it, but chose not to in the end as I thought it was more agg than it was worth if the car ever had to go back into Porsche for anything. They'd probably turn around and say that its the reason for bubbling paintwork or something ridiculous lol. I believe that you can get some sort of code blocker instead of a remap, but the remap is the better option due to altering the way the actual exhaust system works from factory. Think the blocker thing block all codes though, so for example if you had a different error on your car, it wouldn't flash up. I know of a fair few people that have done it, but they're not the PH type, so you wont find them here (not a dig at any of us that use this website!) Instagram would probably be your best bet on that. Edited by F12DDE on Thursday 30th November 12:33 Edited by F12DDE on Thursday 30th November 12:34

F12DDE said: I never ended up going down this route in the end, did talk to some garages about doing it, but chose not to in the end as I thought it was more agg than it was worth if the car ever had to go back into Porsche for anything. They'd probably turn around and say that its the reason for bubbling paintwork or something ridiculous lol. I believe that you can get some sort of code blocker instead of a remap, but the remap is the better option due to altering the way the actual exhaust system works from factory. Think the blocker thing block all codes though, so for example if you had a different error on your car, it wouldn't flash up. I know of a fair few people that have done it, but they're not the PH type, so you wont find them here (not a dig at any of us that use this website!) Instagram would probably be your best bet on that. Edited by F12DDE on Thursday 30th November 12:33 Edited by F12DDE on Thursday 30th November 12:34 I hate what cars have become. I would not remap as I’d want extended warranty for as long as possible. So annoying when you know what these cars should sound like.

I have had the OPF’s replaced on my gt4 by ninemeister as part of their upgrade package. I am now really happy with the sound of the car & the fact you can operate the valves properly via the switch is a big plus. When I bought it it had a straight through sports exhaust fitted with no valves & the drone for me was terrible & you didn’t even gain a better sound because of the OPF’s.

Is that their stage 2 package you had installed, so remap, GBP delete pipes and BMC filters ? do you feel an increase in power too, as its supposed to give 40 odd bhp increase ?

F12DDE said: I never ended up going down this route in the end, did talk to some garages about doing it, but chose not to in the end as I thought it was more agg than it was worth if the car ever had to go back into Porsche for anything. They'd probably turn around and say that its the reason for bubbling paintwork or something ridiculous lol. I believe that you can get some sort of code blocker instead of a remap, but the remap is the better option due to altering the way the actual exhaust system works from factory. Think the blocker thing block all codes though, so for example if you had a different error on your car, it wouldn't flash up. I know of a fair few people that have done it, but they're not the PH type, so you wont find them here (not a dig at any of us that use this website!) Instagram would probably be your best bet on that. Edited by F12DDE on Thursday 30th November 12:33 Edited by F12DDE on Thursday 30th November 12:34 This is not true about blocking ‘all‘ codes. The OBD blockers can be easily set to block a particular reoccurring code. I would argue there is no downside to OAP/OBD-blocker other than warranty, if anything, removing the OPF is better for engine longevity. The standard valve set-up on the GT4 is set to abide by EU noise regs, nothing to do with sounding more refined. The valve mod makes a significant improvement (I used collars rather than disconnecting them). BMC filters also made a significant intake improvement, which makes sense as they are used on the GT4RS.