Just fitted 200 cell cats to my V8V and can’t get them to seal at the rear, not the gasket end. I have fitted that bit first, clamped it up but as soon as you tighten the bolts to the header/manifold a tiny gap (0.5mm) appears and it blows. I have moved the rear exhaust forward as much as possible but the gap is still there. I’m thinking of fitting an extra gasket to the front or exhaust paste, what do you think?Thanks

 

Double gasket? Really! You need to loosen the intermediates at the gearbox and nudge the center forward.

 

My brother sent me some 200 cell cats and I had the same problem. I ended up backing off all mounting HW at the mid and rear sections then use a ratchet strap to pull the section forward, tighten clamp, release strap. It worked.

 

 

I found that giving the h-pipe a hit of PB-blaster near at the back connection made moving it into alignment helped. With that said, on my 964 the 200cel CAT on a tiny bit too small and nothing was going to fix it, I ran a double seal for years and it never leaked.

Goodluck!
Daryl

 

Success so just to close the loop....

Loosened the clamp on the rear exhaust to cat extension on the left hand side of the vehicle; the extension moved (which was a massive surprise) so I pushed it back into the left hand exhaust pipe by 5mm; yanked the full rear system forward so it fitted flush with the right hand cat; bolted that up (one handed as I used the other to keep the pressure on the joint); then slid the extension onto the left hand cat until it too was snug; tightened that clamp up and hey presto no leaks….Sounds awesome I have to say and the engine definitely revs freely….