87FormulaGuy

Hi everyone,

I have an 87 Formula Firebird, LG4 5 speed, and I'm going to be redoing my exhaust in a couple of weeks. Currently there is a rusting original 87 midpipe, a straight pipe welded in place of where the cat would be, and a clogged up muffler.
I was thinking of converting to a high flow cat (3" in/out, gotta pass emissions this summer) and a 3" Hooker Catback Exhaust. I will have to retain the stock exhaust manifolds for now since I don't have $$$ for TES headers; I'll pick them up this summer. As far as the cats, it seems like a Catco is the way to go for under $100. Anyone know the best place/price to get one from?
My main question is about the hooker exhaust- which one to get for my car. At jegs' website there is a part# 520-16822 Camaro/Firebird 1983-85, 305 for $199.99, and a 520-16820 Camaro/Firebird 1983-92, 305(non-H.O.) for $259.99. Can you guys tell me what the difference is, and if I'd be able to use the cheaper one on my car without any drawbacks? I figure I might as well save $60 if I can I was also told I'd have to have custom adapter exhaust pipe installed for the 2 1/4" manifolds to the 3" cat...but since I plan to add TES headers in the future I thought this 3"in/out would be the way to go. Let me know what you guys think of this setup, thanks

Steve

87FormulaGuy

Come on guys, I'm sure somebody has the answers and an opinion on this setup...

Troy 85Z

I bought the $200 cat back which is for cars with a 4 bolt cat. I'm sure you can find a 3" cat with the 4 bolt flange but it may be cheaper to get the 3" slip fit cat back (not sure part #) and 3" cat. First I would find out the price difference for the 2 different cats (4 bolt or slip fit) and see if it is worth saving $60 on the rest of the system. Both systems should work fine though. It will be easier to use the slip fit design in my opinion because it is easier to get the slip fit reducer and you won't have to fab anything. Good luck with whatever you choose.

87FormulaGuy

Thanks for the reply, I called up summit racing and jegs today and got some info on the catbacks which confirmed that. However, the guy at jegs said the stock cat will support 300 HP so I don't even need a high performance one unless I plan on heavy mods to the engine...which I don't for the next couple of years. Anyone know if this guy is right and I don't really need the 3" high flow cat and can just use the stock 2 1/4" ?

Ed Maher

If you can i would upgrade it. First of all, that guy is msoking crack if he thinks a single 2.25" cat will support 300hp, yet another reason to avoid tech line operators.
Your best bet is to wait and do it all at once, with either an earlier styl L69 headers w/ 4 bolt cat, and a 4 bolt cat back. Or, use L98 3" cat stuff.
It will not be worth the trouble to adapt the 3" cat to your stock Y-pipe, nor does it make sense to upgrade the Y when you're planning on headers. there is something to be said for buying the right cat back for your set-up now, ethn cutting the front off and getting that modded to weork with your later 4 bolt/ 3" set-up. Of course, the'right' cat back for you now is $60 more, + it will cost a few bucks to mod it to fit later.
so, in the end, if you are truly on a shoe string budget, wait, do it once, do it right.
...ed

MilehighBird

iTrader: (1)

I agree with Ed and think you should replace the cat at the same time.I was in the same boat a few months ago and waited a month so I had the extra $90 to do both.I got a 3in flowmaster system and 3in catco cat at the same time and everything fit perfect.Still have the stock LG4 manifolds and y-pipe.Slp headers going on next.Good luck with your swap.