I’m getting to the point of putting exhaust on my 89’ firebird. I’m using a set of Flowtech headers part number 11116FLT. Flowtech did note that modification of the factory y-pipe was necessary to retain the catalytic converter. However I am not running the converter altogether, but I was rather disappointed with how much modification was required. Now I found a y-pipe Flowtech makes (part number 11102YFLT) which is noted for working with their short-style headers, but also notes “may require modification to connect to original exhaust. I want to know if anyone has used this combination and what modifications were found necessary to hook to original exhaust. Thanks in advance for your answers.

Did you end up using this setup? I got the same headers thinking they would bolt up, and now have them sitting in their box awaiting install. I'm wanting to use the catalytic, but it doesn't seem Flowtech makes a Y-Pipe for these headers to hook up to the catalytic. I guess technically I can get away with not having it altogether (since my car is older than 25 years and I'm in TX). So, how is this install? What's involved?

Anybody know what it takes to get the Flowtechs on without changing the Y-Pipe? Anybody know of a "plug and play" y-pipe that will work with this setup? Does this setup work without mods if you ditch the catalytic?

I live in Texas also and so you know, it still has to have the CAT even thou our cars are 35 yo it still has to have all smog crap on it for the look over it gets durring the state inspection.

Why not just weld a flange for the cat on to the Y pipe?

I am currently running this setup.

It is a net gain over stock, but I'd suggest holding off and getting something better like Hedman. Even the Summit brand is better quality.

im also running this setup. way better than stock but defenetly not the best. im running catless at the moment and had a muffler shop weld everything up.

I used this set up on my 88 Iroc I had to trim the end that inserts into the flared end it was a close fit used the collecter bolts to pull it all in. ran dynomax cat back exhaust i had the muffler shop run a small section of exhaust in place of the cat, if your o2 is in the header it should not affect anything.

Summit brand is Flowtech.

From what I understood summit had a few different companies they sold. Naturally, chances are pretty good that I am misinformed.

Just a heads up, as someone else already stated, the flared bit will need to be trimmed, or the whole sch-bang won't meet up right. Also, the ypipe is of...questionable quality. That short joiner to the y is very poorly cut, mine had a biiiig hangover. At the time I didn't care. Now that I'm bumping up to a bigger motor, I sure wish i'd bothered to hog it out!

Don't bother trying to save your stock pipes bud. Cats with air tubes can be had for about 80 bucks on summit, and getting a bigger diameter will do you nothing but favors. My whole job ran me 225.00 out the door, plus of course the cost of the bits n pieces themselves. It was fast, convenient, and they even painted the pipes for me lol.

I've got this setup on my 87 and I don't like it. The y-pipe is crap and the flange hits the pass. frame rail, even after trimming the collector. The work but I wouldn't buy them again.

1981LT1

Can you tell me, was there a vibration from the flange hitting the rail? If so, can you explain what kind of vibration? Did you ever get rid of it?

The passenger flange hits the frame rail during idle. I'm really surprised it hasn't triggered the knock sensor! I have tried grinding the flange to make it a little more flat but it still rattles. When i find some time, I am going to drop the passenger header and try and work the framerail a little to gain some more clearance. unfortunately, I can't do anything else since it will cause the y-pipe to go out of alignment and give me a huge exhaust leak. I would really like to replace the entire exhaust but the budget isn't there right now.