Don Carter

That could be my problem. I think my mid support gave out about a decade ago...

Jerome Craig

I used two wraps of this to seal the slots on the rear tailpipes and put the fiberglass wrap over it as per the instructions. I made sure that the bandage butted up against the cats so there would not be any opening between the cat and the tailpipe. I did not, however, have any of the bandage covering the area where the cats and tailpipes joined.

After a month of daily use, I do not seem to have any leaks. BTW: I'm running the x-pipe with GT resonators and GT muffler. There is a bit of a drone between 1500 - 1700 rpm; but the jump in hp and tq is noticeable and the sound as the engine revs toward redline is amazing!

Jerome

Tom in Austin

Dumb question ... why does the maker of the X-pipe have an end which is larger than the pipe it connects to?

Hilton

Actually a good question.

I have two X-pipes, one of the Motorsport SLC ones, and a stainless one from the UK by Ritech Systems (might be spelled wrong).

The UK one bolts up much easier - slip-fit and clamp to the rear pipes, same as the stock cats, and it has an O2 bung at the merge, which I prefer to on each bank.

The UK one does look a little skinny at the merge of the X - I suspect the larger diameter pipes on the Motorsport X were chosen for the optimal cross-sectional area at the merge. I haven't compared them on the dyno on the same car - I should do, just haven't had the chance.

Stan - your point about the mid support is a good one. My '89 was missing it (presumed gone when a rebuilt TT was fitted under a PO's stewardship), and I recently put a replacement one on when doing my TT. I'll order the Heat Sheath and hopefully fix it.

Rob Edwards

Are you guys talking about #'s 6-11 in this diagram? Neither of my cars (despite stock exhausts) had/have this support, I always assumed this was some sort of vestigial appendix-type thing in PET. Where does that #9 bracket attach? To the TT, or the heat shield bracket, or ????

Hilton

7 - the giant hose clamp, holds 6 against the TT.

A rubber exhaust hanger then joins 6 and 9.

The bolt (11) then clamps the pipes between 10 and 9 holding them fixed in position.

The whole lot fits through that neat square hole in the heat shield.

I'll go take a pic in a minute if I can figure out where I left my garage camera, although the heat shield hides a lot of it.

Ispeed

I believe that center support to the TT was deleted when they went to the smaller resonators (mid '88). I have one on my '87 and it is in a great location to support things. I wouldn't go without it.

#7 is a clamp around the TT. You need 6, 7, 8a, 9, 10 and 11.

Tom in Austin

PET shows the center mounting for GTS as well ... I posted about this and seems most people's cars don't have one. I had Sean put one on my '94 last time he was going over things and now the amount of movement in the exhaust system is noticeably less.

Still wonder if these get overlooked when people replace their TT. Would be easy to overlook putting #7 onto the new tube and once you finished that job who would go back and take care of it?

jon928se

I've seen so many 88+ cars without these that I reckon either PET is wrong or the factory just forgot to fit them. It would be interesting to see how many Porsche AG have in stock - if it's in the 10s of 1000s it would prove my theory.

For those that want to fabricate their own the clamp for the pipes is an exact replica of the clamps that are used to to join sections of temporary construction site fencing together ( the kind of fence that is a panel of mesh about 6' long and about 5' high, surrounded by a 2" tube with a downstand leg at one end that sits in a concrete "shoe" with a 2" hole in it." And I never told you to "borrow" one. They also use this type of fence at open air rock concerts.

Ketchmi

The reason the crossover designer made them with a 2.5" tube is to allow fittment to the now released 2.5" cat back system. I saw no reason to create horsepower then neck it down when it would need to be reworked at a later date for those that want even more power. (always looking ahead!) The intent the whole time was to create a full high flow exhaust system, not just a single piece. There are so many options available to connect it to the factory cat back that it is up to the customer as to how they want to do it. The fiberglass tape I send with them has worked for me for years when done properly.

I am sure that there are easier and better ways according to each customer to connect them in each situation but as you are seeing, every situation is different. Missing the center support allows more flex and can work the fiberglass out. I can't send center supports along with each crossover "just in case". Quite a few of our customers actually weld them onto the catback...done deal. If the aluminized tape works for you...use it. If you want to use tubing reducers, feel free! It's entirely up to you as to your preferred method of attachment. If someone comes up with a failsafe connection that is cost effective and works for everyone I would be more than happy to use it.

Some of our customers have had 3-bolt flanges welded to the end of the crossover and the front of the cat back. That would be the preferred method but would preclude installing one at home for most people. If you really wanted a nice setup, a V-band clamp with flanges would be sweet but would also have to be welded on.

Bill Ball

I think you could be right about the deletion of this support in 89. My 89, which I know was never messed with, has none of these center support parts.

I installed the SLC x-pipe (from Roger) over a year ago. Very soon after that, I swapped in an 87-88 (large resonator) exhaust cat-back (with my existing RMB) to manage the noise, which was way too loud with the small 89 resonators. The 87-88 large resonators really helped tame the exhaust note - still mean sounding when jumped on but not offensively loud and much more tolerable when cruising. I still don't have the center support. Despite that and only using the fiberglass packing Roger provided, the exhaust has no noticeable leaks. I do have the clamps TIGHT as Stan recommends. Although I did it with hand tools, the band is nicely deformed around the joint and hasn't lost the packing in the year or so it's been on.

Rob Edwards

The center support parts are still available from Porsche for about $50. I'm pretty certain the exhaust on my GT was never touched before I got it, and there was no sign of these clamps it.

I also had good luck with the fiberglass wrap and tightening the hell out of the clamps so they deformed around the connections:

dprantl

I don't think anyone was messing with the TT in my GT before I rebuilt it. I did not have any center exhaust supports on the TT.

I also have a problem sealing my cats to the catback. The problem is I may have tightened the band clamp bolts too much. As you can see from Rob's picture above, his clamp edges are already tucking themselves under the metal divider on the cat side. This is what happened to mine except worse.

Dan
'91 928GT S/C 475hp/460lb.ft

fraggle

My '87, #1608, doesn't have the center clamp hardware, but it make have been removed before I got it. However, considering the condition I've found things I have my doubts.

worf928

Here's my secret to a no muss no fuss x-pipe install:

http://www.jegs.com/i/JEGS/555/30732/10002/-1