What is the size of the collector on a 1988 5.0 GTA Y pipe? Is it 2 3/4" or 3"?

What do you mean by "collector"?

By "collector," assuming you mean where it slips into the cat, the Y-pipe on a TPI is 3". The cat is 3" in/3" out. The intermediate pipe to the muffler is 2 3/4".

Yep, where it bolts to the Cat. Thats what I wanted to hear.

The ID of the pipe is 2.75"... GM used very thick pipes on these cars for some reason.

The OD might be 3", but that don't mean chit because the pipes are so thick. Its about 2.75" ID.

Exhaust pipe is measure by OD, not ID. And OD is 3" where the Y-pipe slips into the cat on engines 7, G and F, prolly 8 too. And the cat's inlet is 3". So 3" do mean chit. The pipe itself is about 1/16" thick, so ID is about 2 7/8".

Basically what I am trying to do is make sure a 3" pipe will fit directly onto the Y pipe without any modification.

Your Y-pipe is BARELY 3" OD, maybe a tiny bit smaller, so it MIGHT slip into your new 3" pipe. But more than likely, you'll have to have the end of the new pipe expanded(like the cat inlet) so it will slide over the Y-pipe. But expanding it's easy. You could rent an expander from Auto Zone(money back upon return--so it's actually free), or you could take the pipe to a muffler shop and have it expanded for like $5.

The AZ ones sometimes aren't up to the task(I've broken one, lol), but since you'll only have to expand it a very small amount, it might work. But a muffler shop can do it easily. Just don't let them make it too wide.

I dunno... when I cut my L69 pipe, it was quite a bit thicker than that...

Ok. Let me get a little more technical. A flared 3" pipe will fit directly over the Y?

Yes

Phew.....That's the answer I was looking for...

yeah tlel me it took us 9 hours for a header job that shoulda been 3 hours.

For now Im going to cut the cat and the rest of the crappy exhaust off the car and clamp my 3" 40 series flowmaster where the cat is supposed to be and dump it right at the muffler. Watch out ricers and your fart pipes, here comes a real car... :rockon:

hehe wont be near as loud as mine d00d.

mine sounds like a top fuel drag car.

I'll get a sound clip tomorow.

Get out of the house and go to a track, your car sounds NOTHING like a top fuel dragster.

my car doesn't have the steady idle thata top fuel has, but the thing is just as loud, dB wize.

i just got my 3" put on and the stupid y pipe was only liek 2"3/4

Uhm, wait a minute, i know its here someplace,. Ahh here it is..

Well, over the weekend I cut off the entire cat back crappy exhaust including the cat. Took me 3 blades on the sawzall to get the cat cut off the pipe. Put my 3" Flowmaster on the Y pipe and it sounds like ***. Need some more pipe behind the muffler to tone it down to a normal Flowmaster sound. Just sounds like a car with a broken exhaust.