Stock Y-Pipe
 

What size pipes is it on a LT1 F-Body Y-pipe with a single cat, before it goes into the catalytic converter?

2.5???? :shrug: i don't really remember....

I always thought that it was 2.75", but I've never measured myself or anything....

- Justin

which pipes? i have my stocker sittin right here that i can measure...u want the inlet to the cat? or the diameter of each pipe before they merge?

The actualy Inlet to the cat is what Im looking for. Where the two pipes merge.

inlet to the cat is 3" i.d.

Can someone help explain the pipe I need?

It would be to connect a 3" exhaust pipe from the stock y-pipe to my 3" cat-back.

I think it would have to be:
3" Pipe
with a 3" ID and 3" OD (or ID) on the ends?

ex:
http://i12.photobucket.com/albums/a2...5/cat-less.jpg
I hope someone knows what Im talking about :lol:

What im trying to do is cut out my stock cat with a saw-zall. Â*And connect both ends with a 3" Test-Pipe, and clam the two ends down with band-clamps, so that the pipe can easily be swaped out or removed.

MY y-pipe has a 3" end/stock cat 3" inlet... yours is the same, I assume.

For your test pipe get 3" OD on both sides and you shoudl be set, i think

dude again I highly doubt your y-pipe is 2.5" considering v6 ones are 3"

out/out

Mac makes the pipe you need for 84 bucks or so, check this out.

http://www.macperformance.com/store/...Product_ID=498