Well, I think my 2.8 V6 to 305 conversion on my 88 Firebird will get put on hold for a while... this weekend I found a nice solid 89 GTA... 305 with a 5 speed... bright red with grey interior... I'll be bringing it home probably tomorrow. I can't wait... I've always wanted a GTA... so when I found this car I couldn't pass it up!

Question... one of the major problems with the car is it has dual cats, but the cats are shot. I need to replace them for emissions testing... what is better, stick with the dual cats, or go with a single high flow? Any suggestions?

 

If you don't have visual inspection I would go with a single cat. You will have more room down there and the total cost will be much much cheaper in the end.

 

Would a single high flow cat produce less power than replacing the stock duals with two high flow cats??

 

You can get new cats for $30 on Ebay..

 

This is the first time I've heard of a dual cat system being a problem. IIRC that was a fairly rare part (if you want to replace the entire unit with a factory new part, be prepared to spend at least $600 or $700.)

Yes, replacing two cats is going to be more expensive than one, but I think GM rated the engines with dual cats about 10 hp higher than a single cat.

 

That is because they used two restictive cats instead of one. A single high flow 3" cat can support 350 hp to the wheels before it becomes a restriction.

 

Yeah, GM parts are expensive... even after a GM discount (my dad's a GM employee so I can get GM parts cheaper!) they were still almost $500 per cat!!! That's ridiculous!!! So aftermarket it is... I priced out some aftermarket cats, at $180 each installed. That's a little easier to take!

 

Is there any difference between High-Flow Cats?
I mean, I can get a generic (or not too popular brand) one for $70 Canadian, and yet Spintech makes one that I can pickup for $100 (also Can.) Would there be any difference between these two high-flow cats?

 

Well, I picked up my GTA last night and drove it home. The car drove great. What a difference between driving the GTA and my 4 banger S10! The car hasn’t been driven for over a year, but it ran great, even with the exhaust leaking from the shot cats. The car needs a little work (I’ll be searchin through a couple of the other threads on this site) but overall it’s a good solid car, I got it for what I think is a good price, and I hope to have it safetied and emissions legal in the next week or so.

 

Cool got any pics of it yet??

 

Not yet... hopefully soon...