Hey guys, I've never done any exhaust work before so I thought I'd ask a few questions first.

To start off I have a 1987 Trans AM 305 LG4 of badness.
I'm looking for some cheap headers to help the mongrel breathe a little better, nothing to expensive you know, it's an LG4 after all.

I've arrived at the cheap Summit Headers: http://store.summitracing.com/partde...part=SUM-G9005

From a previous thread I found out that the Summit headers are identical to the flowtechs, so the flowtechs Y-pipe can be used with them to bolt right up to the cat.

The Y-Pipe I found is: http://store.summitracing.com/partde...=BIG-11102YFLT

Now down to my question, the collector is a 2.5" which matches up with the Y-Pipes 2.5" inlet diameter. However, I'm looking at possibly getting a new catalytic converter as well since my current one was gutted by a nasty backfire (banana pealed the muffler too). However I cannot find a catalytic converter with a 2.5" inlet to match the Y-pipes 2.5" outlet. Is this because the catalytic converter is a slip fit? So you slip the 2.25" catalytic inlet inside the Y-pipes outlet, then tightened them together? This is what common sense has led me to. Probably a dumb question, but this being my first time touching an exhaust I just wanted to make sure.

Thank you,
Austin

 

No one can answer this?

 

DONT WASTE YOUR MONEY AND TIME.
if you are going to do a little building and drive it on the street you need one with an oxygen sensor and air intake.
if you are going to do that you should get a 3 inch y pipe and let it breathe right.
you are already limited by the stock heads and the 2 1/4 exhaust so open it up.
try hooker 2055's with a 3 inch y pipe and they are smog legal.

 

why do you want stock size piping my factory iroc y pipe is bigger then that. get some hooker shortys and a 3inch cat back. hooker painted have all emision hookups and an o2 bung

 

I'm with tony here, I personally would never put anything like that on my car. The 2055's are much better, compare the y-pipes, the one you provided is is the flowtech one, look at it, it looks as if the pipe travels in almost angles instead of bends.

Go with the 2055's save your money for a couple months and buy something good.

 

I don't understand this obsession w/ y pipe sizes, Why run a 3" y when you have a 2.5" cat back?

EDIT: and to keep it on topic, the Summit ones are apparently good enough for mild-mid built 305's. I'm considering a pair myself, but i'm going for a budget build, nothing too fancy.

 

Because there's a big difference between a 3 in. y pipe with a 3 in. muffler on the end, and a 3in. y pipe with a 2.5 in. muffler on the end.

The 3 inch y pipe is necessary for exhaust flow, and as the exhaust travels farther along the exhaust system the pulses "weaken" and if a smaller cat back than the y-pipe is used then it will result in the same flow rate throughout or as some cat backs boast, improved flow numbers.

It's like when you hold a water hose with the pressure at a moderate amount, if you cover the opening halfway the pressure builds and it goes faster.