Modified 3.4/3.6 Mufflers Exhaust - Virtual PSE apparently..

http://forums.rennlist.com/rennforums/showthread.php?t=304600 On the Rennlist forum there are many posts Re: a cheap (circa $200) modification to the standard mufflers which will result in a VIRTUAL (non switchable) Porsche Sports Exhaust like sound. This COULD be a good solution for owners of older cars which are long past warranty and who want a cheap fix. Not recommended for newer vehicles obviously!! Has anyone tried this in the UK (these are all USA ones on the Renntech forum)? Edd Copied from Sid911's post:- I'm not for or against either arguement. But I find it hard to believe that there is some special "porsche blessing" on the PSE mufflers. When compared to the modded mufflers (modded in a certain manner, explained below) they are identical in all respects. Laws of physics. They have the same internal shape, same materials and same gas flow volumes. The only way they can be different is if People are calling ANY mod to the stock mufflers the "PSE mod". There are hundreds of ways you can mod the stock muffler (size of pipe, start/end point of that pipe etc). But the PSE is just one such a combination of those variables. Something I don't really know or haven't yet understood. As an engineer, given the data I cannot see why the performance would differ unless there is an important fact I'm not even aware about. I'm thinking the reason you find a lot of differences in the sound when comparing modded mufflers to the real PSE could be due to #1. Of course, if its #2, I'd love to know more about the differences. About the PSE mod. The 1st version of the real PSE was based off 3.4 L engine mufflers. There was a J style bypass pipe (3/8") from inlet to outlet. The 2nd version of the real PSE was based off 3.6L engine mufflers. They had a L shaped pipe from the 2nd chamber inlet to the outlet pipe. Basically you let the air pass thru the 1st chamber as usual but as it almost enters the 2nd chamber you bypass a part of that volume it out to the outlet. So some of it goes out and some of it goes thru the entire 2nd chamber and the entire 3rd chamber. How much of air passes thru each route is determined by how wide a pipe you use as the bypass. The real PSE's bypass pipe has the same diameter as it outlet pipe. Note that the 3.4L engine based mufflers and 3.6L engine based mufflers are different internally. So doing one mod on the other won't get you exact PSE sound. Finally, the real PSE also has a cut off (vacuum actuated) valve (open/closes bypass pipe) electronics to control that valve (when to let the vacuum in, when not to) So when the above two are working the acoutic model changes. So you basically switch between "stock muffler" and "PSE" dynamically on the fly (as determined by the electronics, based on your current speed) Most people doing the mod don't want such a cut off (i.e. PSE->Stock) zone. This is what keeps the mod simple, managable and less prone to "manufacturing" errors. If they actually want such a cut off, it becomes a very complicated mod, and you're better off getting the PSE. The fact is that a lot of people installing the real PSE keep the mufflers in "always PSE" mode by cheating the electronics or cheating the vacuum valve. Hope that helps ! Cheers ! Sid

Gizmo750 has them... http://www.911uk.com/viewtopic.php?t=37869&postdays=0&postorder=asc&highlight=weld&start=10 You may also want to check www.6speedonline.com , loads of info there about the 'hack' like best pipe diameteres, difference between 3.4 and 3.6 boxes etc etc.

Cheers Stuart, useful stuff Edd

Indeed I do and I'm happy to answer any questions you have. I'm happy with them too, the only thing I don't have is the switch obviously but for a total of about £300 I can't justify the extra £1100 + for the PSE on a 7 year old car.

+1 Brilliant sound. Here's the ones I modded for mine:

So all you did was weld the pipe over ? Not touch the inside at all ????

There were two types of PSE. The original one fitted to the 3.4 litre cars had a bypass pipe between the inlet and outlet pipes to the silencer, with a valve in the bypass. That's often referred to as the Mk 1. What I did was to replicate this, but without the valve - just an external tube. That's the same way Oettle do it. The later PSE has a much larger pipe and valve which bypasses PART of the silencer. This is mostly referred to as the Mk 2. Some people also do this as a fixed bypass modification. The valve on the Mk1 PSE wasn't switchable when factory fitted, but I believe you can retrofit the switch control. It was originally speed dependent. The Mk 2 system is switchable, but has an annoying quiet band at low speeds. This can be disabled by cutting a diode in the relay, or disconnecting the speed signal to the relay. Porsche say that you shouldn't put a 3.4 silencer on a 3.6 car, but it's OK the other way round. The trouble with buying a system from Oettle is that you don't know what it has come from. I bought a set of new 3.6 silencers for £100 on eBay and welded in the tubes. The Mk 1 and Mk 2 mods have a different sound, but I was chuffed with the sound of mine. I didn't track it though, which is a problem with all the bypass mods, and most aftermarket exhausts. By the way, the answer to your question is 'Yes'.

Hi Richard, Great post! I have been doing loads of research and think i am going to mod my stock boxes as cannot justify the cost of PSE! I have been reading loads and can i ask what diameter u bend did you use? I have read some people using 1 inch and some saying 2 inch is the best to use. I guess the wider the u bend the more sound you get....

Is there a way of looking at the boxes to see which are which ? (3.4-3.6) I know you can see on the PSE MK1 - MK2 as the pipe for the PSE is smaller on the MK1 ?

The silencer pressings are the same, so it's impossible to tell from that. The part number should be stamped on them, but I have a theory about how to tell the difference by looking at them. It seems that all the 3.6 silencers have the 'accordian' flexible section in the inlet pipe. as shown in my photo. On the 3.4 cans there is either no accordion, or one which has much finer pitched accordions. As I say, just my theory, but it hold up on all the silencers I have seen.

http://cgi.ebay.co.uk/Porsche-996-S...39:1|66:2|65:10|240:1318&_trksid=p3286.c0.m14 I would stop posting about how you welded your own boxes Richard ! Or people may start PM'ing you about a cost to do these standard boxes ! :wink: :wink: :wink: :wink: :wink: :wink:

If you want cheap bypass valves for track days how about these? Photo courtesy of Tool Pants on Renntech - not sure if it's a joke or not.

:floor:

Hi Richard, Is this correct that you can use mufflers from a 3.6 996 on facelift on a 3.4 996 non-facelift? Are they the same size with the same fixings, etc?

Yes - exactly the same - that's what I did on mine. Only the tips are different. The facelift tips have slightly longer tubes between the silencer and tip, because the rear PU is a bit deeper.