Anyone have this catco #4115 cat on their car? I've gotta do some welding on my exhaust tomorrow - the y-pipe end keeps cracking at the inlet, no matter how much metal I've already added to it- and I'm going to just cut the end off the y-pipe and replace it with a length of "new" pipe. I have the feeling the end of that y-pipe is very fatigued; when I weld in a new patch of metal, another section of the pipe cracks.
So; Summit's website's description for the cat says it's a 2 1/4 inch slip-fit inlet. But, I remember when I installed it, the 2 1/4 inch clamp was too big- so I put a 2" clamp on, and it fit fine.
Going by that I've got a 2" clamp, I'm inclined to think the bolt-in replacement cat also has a 2" inlet, but I'm not sure.
(Background... I have an aftermarket Y-pipe made by AP on my car. When I put one inch lowering springs in, suddenly I'm scraping my exhaust everywhere. The y-pipe started to fatigue and crack at it's lowest spot- right before the cat; where it kept getting hit. The aftermarket y-pipe doesn't hug the floorboards like the original GM pipe did! So I'm sectioning that y-pipe and re-doing the angles so it DOES come near the floorboards. You can actually see my y-pipe-to-cat connection sticking out from under the car!)
Yes my car is a v6 but we use the same cat that you V8 guys do
So; Summit's website's description for the cat says it's a 2 1/4 inch slip-fit inlet. But, I remember when I installed it, the 2 1/4 inch clamp was too big- so I put a 2" clamp on, and it fit fine.
Going by that I've got a 2" clamp, I'm inclined to think the bolt-in replacement cat also has a 2" inlet, but I'm not sure.
(Background... I have an aftermarket Y-pipe made by AP on my car. When I put one inch lowering springs in, suddenly I'm scraping my exhaust everywhere. The y-pipe started to fatigue and crack at it's lowest spot- right before the cat; where it kept getting hit. The aftermarket y-pipe doesn't hug the floorboards like the original GM pipe did! So I'm sectioning that y-pipe and re-doing the angles so it DOES come near the floorboards. You can actually see my y-pipe-to-cat connection sticking out from under the car!)
Yes my car is a v6 but we use the same cat that you V8 guys do
Senior Member
I put a 4115 on my car last april. It is a 2-1/4" ID inlet. Just to make sure, I just checked the fit of a 2-1/4" clamp on the cat at the y-pipe and it fit perfectly.
No kiddin... huh. Maybe I'm remembering all this wrong 
I guess I'll have to take another look in the morning! Thanks for the info!
I guess I'll have to take another look in the morning! Thanks for the info! Hey thanks again, bru333! You were right, it -was- a 2 1/4 inlet. (I must've tried a 2.5" clamp and went to 2.25, instead of going from 2.25" to 2".)
I cut out the bad elbow, and replaced it with a home-made adapter. Since I've got a a V6, my y-pipe is 2", and it flares to 2.25" for the cat- the local store only had a 2.0" OD to 2.25" I.D. adapter... of course I needed 2" to 2.25" OD!
So I also bought a 2.25" ID to 2.25" OD adapter... I cut both in half, and made my own 2.0" OD to 2.25" ID adapter. A little more measuring and cutting and now I've got that "new" metal in place... and it sure is thicker than the old worn-out elbow!
Thanks again!
I cut out the bad elbow, and replaced it with a home-made adapter.
Since I've got a a V6, my y-pipe is 2", and it flares to 2.25" for the cat- the local store only had a 2.0" OD to 2.25" I.D. adapter... of course I needed 2" to 2.25" OD!So I also bought a 2.25" ID to 2.25" OD adapter... I cut both in half, and made my own 2.0" OD to 2.25" ID adapter. A little more measuring and cutting and now I've got that "new" metal in place... and it sure is thicker than the old worn-out elbow!
Thanks again!