Fitment issues with Top Gear catted 200 cell x-pipe.

One of the factory cats on my 46K-mile '02 Carrera cabrio started rattling. I settled on a Top Gear x-pipe with 200-cell cats. https://www.topgear.co.uk/porsche-91..._type=exhausts (I already have the Top Gear loud sports mufflers and was pleased with the sound, quality, and price.) Unfortunately, they were initially out of stock on the Top Gear website and I couldn't find any US-based vendors that had any in stock, so I ended up waiting. Then a couple weeks ago, the Top Gear website indicated that they had 20 in stock, so I ordered. The x-pipe arrived last week and I dug in this weekend. I got the existing mufflers and cats removed, but when I tried to test-fit the x-pipe, I found that the cats would touch the heat shield above them, even without having the bolts to the headers tightened. My 996 has Torque Solution semi-solid motor mounts, which raised the engine slightly. I switched back to the factory motor mounts, which were actually still in good shape, but that didn't lower the enough engine to make a difference--the cats still touch the heat shield. I emailed Top Gear and got the following reply: " I showed this to our techs and they advised as follows- "Looks to us like the engine is still sitting too high. The flanges will pull in once the bolts are fully tightened we are sure" We do sell hundreds of this part and they are direct fit to all 911's. Best Wishes, Alexander Kilcoyne Director Top Gear (Bridport) Limited " I replied: "Thanks for the quick reply. I don’t understand.. how can the engine still be too high if I’m using the stock motor mounts. I don’t know how I can lower it any more. I didn’t have any clearance problems with the Torque Solution motor mounts and the stock crossover pipes and catalytic converters. Since this x pipe is from a new batch (the Top Gear website was out of stock on this part until recently), is it possible that something went wrong with the new batch? Thanks!" That was two nights ago--I was hoping for a reply to be sitting in my inbox this morning, but no. (Top Gear is in the UK and I'm in the US, so the time differential is an issue.) What do you guys think? The Top Gear website now indicates that there are 18 in stock, not 20--presumably the two that have been sold are myself and one other person.

Hi there, from my experience, follow up emails from Top Gear have been hit or miss. Sometimes I get a response right away... Other times - crickets. Do you have the larger diameter x-pipe? I installed the standard-bore x-pipe with 200 cell cats, along with their headers and mild boxes and it all fit OK. I doubt that their headers sit lower than the OEM headers, but I guess that is a possibility. Did you have any issues aligning the ends of the cat pipe to the muffler inlets and getting the clamps tight? One other thing to mention - I used OEM clamps for the cat to muffler and muffler to exhaust tip connections vs the cheap stuff they sent. Good luck with it! Bill

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So far I've sent Top Gear five emails and only gotten one response, right after I sent my first email. I even sent them pics of everything tightened up like they said to do, showing that the cats are DEFINITELY pressed up against the heat shield. I went with the stock-sized x-pipe as I'd heard that the larger diameter one could cause CELs. Haven't bolted the mufflers to the x-pipe yet. If I don't hear back from them, I'm going to file a dispute with my credit card and go shopping for an x-pipe elsewhere.

Just got a reply from Alexander at Top Gear: "Sorry for the late reply. We have some of the previous batch we have compared it to on our jigs, and in addition we have sold others from the same batch without issue." So, I'm stuck. I don't know how it can be something "wrong" with my car when it's all stock and the factory cats fit perfectly, but Top Gear insists it's not them. Do you guys have any suggestions?

I'd try to tighten everything down and take the car for a quick spin to put some heat through the system and see if that helps it "loosen" up.

Is there no give in the heat shield? In my experience, even high dollar exhaust systems sometimes require a bit of tweaking of surrounding shielding to eliminate interference issues. I�d be annoyed if it required any major modifications to fit, but a bit of bending by hand or a tap with a mallet to the shielding here or there isn�t something that is uncommon with exhaust mods (at least in my prior experience) I had to do some light tweaking with the drivers side of my fabspeed exhaust to get it to line up properly

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If you look at the picture of the top of the cat, where it touches the heat shield, there was some give in the heat shield that allowed me to get the bolts on the flanges tightened, but when I tightened those bolts, the cats pushed up on the thin heat shield and bent it so that it's pressed up against the thicker, unmovable heat shield above it. If I try to start the car and the engine rocks, it'll put even more pressure on the heat shield, and stress on the exhaust itself. The mufflers line up with the x-pipe outlets (well at least the left side does--I haven't tried the right side) so that much is fine--the cats are just too high.

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It was hard to tell for sure from the photos on my phone! That�s super frustrating to deal with!

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what's the diameter around the center of the cat ? - I have an uninstalled set that appears quite different 13.5" around the center of the cat - yours look fatter

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I measured around the cats, and they are about 14.2", which works out to a diameter of 4.52"; if yours are 13.5", that works out to 4.3". I don't think that's enough of a difference to make them fit as opposed to not fit, but it's still statistically significant. However, I pulled my x-pipe to take some better pictures of it, and it appears that the design of mine is noticeably different than the one pictured on the Top Gear website. Specifically, the 180 degree bend in the middle appears to be sharper, and the distance between the cat and the parallel-running exit pipe is a lot tighter, in the picture posted on the Top Gear website compared to my pics. The page for the 200-cell x-pipe with 54mm tubing: https://www.topgear.co.uk/porsche-91..._type=exhausts I've posted several pics from Top Gear and of my x-pipe from comparable angles to illustrate the difference. (The last Top Gear pic is from the 200-cell x-pipe with the 63mm pipe, because there wasn't one of the 54mm pipe from that angle. In that pic, the angle looks tighter, and the cats look smaller, too.) The location of the O2 sensor bungs is different, though I'm not sure if that means anything. Top Gear's 200-cell x-pipe website pic. My 200-cell x-pipe. Top Gear's 200-cell x-pipe website pic. My 200-cell x-pipe. Circumference of converter is approximately 14.2". Top Gear's 200-cell x-pipe with 63mm pipe website pic. My 200-cell x-pipe.

A couple more pics. These are comparing the 63mm x-pipe (because the 54mm wasn't available in this angle) to my x-pipe, where it's clear that the gaps between the cats and the exit pipes are much smaller on the x-pipes pictured on the Top Gear website. Also, a picture of the jig that they use for test fitting, which doesn't appear to take into account the location of the cats, hence why it would be easy to test-fit an x-pipe and think that it's okay when it's actually not.

any progress on this ? wondering if there has been any communication from TopGear

Not sure if this helps or not, but here are some photos I took before my system was installed in March 2019.

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Alexander said he would be willing to let me try the 63mm-pipe version.. I asked him to confirm if he thought it would be less likely to interfere with the heat shields, and am waiting to hear back from him.

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The angles of those bends look pretty similar to what I have now. Wondering if the bends on the 63mm version are tighter, like they appear to be on the Top Gear website pics.

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I pm'd you a couple of pics

as requested -

I ordered the 63mm pipe. It arrived and its dimensions were noticeably different from the 54mm pipe--the cats are much closer to the exit pipes on the 63mm version.

Hopeful, I test-mounted the x-pipe. I discovered that if I bolted one side to a manifold, the other side would be at least 1/4 inch misaligned with the bolt holes on the other manifold. I reached out to Top Gear, and their tech told me to slide the bolts through both sides at the same time, and then slowly tighten the nuts, as this would cause the two surfaces to line up. I told him that I didn't like that idea, because I felt like it would put stress on the manifold and potentially crack it.

Then I had a bright idea--what I used a spacer to move the x-pipe slightly away from the manifolds. Since the manifolds are angled in and the x-pipe tips are angled out, a spacer might be enough to get things to line up. To simulate a spacer, I put nuts on the bolts on the x-pipe and then pushed the exposed threaded area of the bolts through the holes on the manifolds. It worked! I then loosely test-fit the mufflers, and they seemed to fit too!

I reached out to Top Gear, and their tech agreed to send me some spacers, gaskets, and longer bolts. They showed up yesterday, and I went to work getting it all together. It was a pain to get a spacer and two gaskets on each side of the x-pipe to line up with the manifold without me dropping something, but I eventually got it bolted up. Everything fit properly, though it did take some "leverage" to get the muffler inlets to line up with the x-pipe outlets since the x-pipe's slightly-rearward location made those two pipes slightly offset. (Basically, instead of putting stress in the exhaust manifolds, it's now been transferred to the mufflers, which are on mounts that are a lot more flexible.) I went for a test drive, and there are no leaks, and it sounds BETTER! Not really any louder (yet) but more of a thrummy exotic note in the upper RPM range. Of course I forgot to take pictures of the completed setup as I was excited to get the car off the lift and tested. I'll take some pics next time I'm under it. I've contacted the Top Gear tech to let him know that the issue is resolved, and to request that he send me a DHL shipping label to send back the originally-ordered 54mm exhaust.

Follow-up. Top Gear sent me a shipping label to send back the 54mm exhaust, and gave me a credit for the full purchase price, so I am happy with how those guys made good on the whole deal. The 63mm 200-cell x-pipe is still installed. It sounds much better than the factory pair-of-triples non-crossing exhausts. On top of that, there seems to be a healthy bump in power. I'm not one whose SOTP dyno goes gaga over small upgrades, but in this case, I think the change is noticeable. Below 3000rpm, there might be a small loss on power. Small. As in, the car gets past this RPM quickly enough that it's a non-issue in daily driving. 3-4K feels a little stronger than normal, but from 4K on up to 7K, there seems to be a noticeable bump in power. Like, it's extra rewarding to run the motor out past that. I wouldn't be surprised if the dyno said there were 20 extra ponies in the stable. Given that literally every other x-pipe manufacturer wants double the money of Top Gear's systems, and given that it seems to be made of quality materials and craftsmanship, and given that your 911 will sound extra beautiful after install, I recommend the Top Gear 63mm x-pipe. Just be sure to ask for the spacers and extended bolts that I got, in case yours doesn't line up out of the box. Oh, I also bought a pair of spacers for the rear O2s, just to be sure that they don't throw any codes.

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Just curious if you're still running these and can give a long term update. I'm considering this for a little extra noise.

Not the OP, but you can check out my similar setup's sound on a track here: You Tube I do not have their headers, just the catted x-pipe and backboxes. I love how it sounds on full tilt and it is very neighborhood friendly otherwise.

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I sold my 911 a couple months ago, with 51K miles on it, and this exhaust was still fitted. I was happy with it, and to the best of my knowledge, the current owner is as well. Last I checked Top Gear UK's website, I couldn't find the exact same parts on it, so I am not sure if they've changed how they're listing the exhaust parts, or if they're just not making them any more. That said, I highly recommend the X-pipe over having two separate, non-crossing exhaust paths. It sounds much better and makes more power according to my butt dyno.

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That sounds great!

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I was going to actually ask about the specific one you got, since i only see the 63mm xpipe on their site. But good to hear you were happy with it overall. Curious to know what you replaced your 996 with.

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How long did it take you to get them to email back? Ordered the 63mm x-pipe and told them I needed the spacers and longer bolts and extra gaskets like you mentioned and of course mine arrived without those items.

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What size O2 spacers did you get if you remember?

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I asked but they didn�t provide the spacers or bolts. Also did you end up using the brackets for the x pipe?