IM thinkin of replacing my exhaust system. Im gonna remove my 3 inch single pipe/cat sys, with a 90 dual cat system. Everything is gonna be replaced, from exhaust manifols, to the muffler. I ordered the 2 cats, y pipe, and the manifolds. What else do I need? I cant go all out like u guys, cause once again of the money factor. Will i gain anything? Will i have a problem with my 02 sensor? I need help guys.


THANKS

 

You're replacing the manifolds with new manifolds?

Aside from the cats and y-pipe you need real headers, and then a good cat-back exhaust system of your choice. There are a handful of different brands to choose from.

 

so are the manifolds headers? OR can i use the ones i got on my iroc right now? i aint really got that much money for a whole system set up. U Live in Chico? Thats where i got my blue iroc. lol.

thanks

 

No the manifolds are manifolds. I'm assuming you already know what the manifolds look like. This is what the headers could look like:



That is a picture of the Edlebrock Tubular Exhaust System for our cars. You see the headers and the y-pipe and the difference between headers and manifolds?

You can use manifolds but they simply are not as good as having headers. You said you wanted to replace the whole exhaust, that would mean headers -> y-pipe -> cat. converter -> to cat-back exhaust system. Also, why do you want to go from one cat to two? One is bad enough. *I may be wrong so double check w/ someone else* but I would just get the headers/y-pipe, hi-flow cat, and then a complete cat-back system to finish it off.

So you would need:
1) something like the Edlebrock system above
2) a hi-flow cat
3) a cat-back system (Flowmaster, Hooker, etc. check summitracing.com )

Good luck.

Oh, and actually I don't live in Chico anymore, Roseville now.

 

Here's a better picture of what that Edlebrock system looks like all put together:

 

Since you're in California too, you can also go with the Hooker 2055s. Them and the edelbrocks (and SLPs I think) are the only smog legal headers around.

 

Yeah i was thinkin of the edelbrocks, BUT, didnt cars(IROCS) with dual cats have an extra 10hp, i mean im gettin hooked up with a good deal, but i want my final questions are, can i make it dual cat, and will it pass smoge, and do i use my stock MANIFOLDS for it, and what else do i need other than the cats and the y pipe?

 

Well, the cat is a bottleneck in your exhaust, so I dont know why you'd want two of them instead of one. Like I said, I may be wrong, but I would just get a high-flow cat and keep it single.

Plus, adding another will really take up some space down there. I'm sure it would pass smog just fine with either one or two of them. But I dont know why you'd want two.

And finally, yes you can keep your stock manifolds and replace everything else....but why? Now you have ****ty stocl manifolds and nice everything else, now your manifolds are a bottleneck.

If you're gonna keep manifolds I would just get a cat-back system and nothing more. If you want to do it all, then get headers, a high-flow cat, and a good cat-back system.

 

I'm not sure I understand the logic behind "NOT" using two cats Timmys88z. Yes, they are a restriction, but having two ultimately flow twice as well as one. Sure, it'd be nice not to have any, but.....that's not legal. As for a high flow cat, yeah that's a given, whether one OR two. I don't think I'd spend money on a dual cat set-up, but yes...it helps. (G92 anyone?)

(just re-read) Since it's off a 90 Iroc, I'd agree with Timmys88Z. Save the money and by a hi-flow.

As for legallity, If the car was offered with 2, you can put on two, even if it didn't come that way. Since you could buy dual cats (G92) in 89, then yes, it'd be legal. I noticed your Iroc decals on the leading edge of your door. Are you SURE it's an 89? Wheels are correct, just checkin'!

 

I mean if the 2 cats were almost given to u would u take them and put them, on? Its been said that those cars with the g92 have an extra 10hp. My friends iroc souns way more better than my car with dual cats, i dont really care about clearance, people be talkin about space issues, im not the type to really build up a car im not gonna go all out with headers, cams and all that stuff, although i am plannin to buy slp's. But thanks guys for helping me out on this one, oh yeah can i keep my o2 sensor, on my friends i think its 3 wires, would i need to change it?


Yes, ive been told about my decals, and yes my car is an 89 i checked the vin and the documents on it.

 

Factory cats were more restrictive than what's available today. Two 2-1/4" factory cats flowed more than one 3" factory cat.

With high-flow cats, the difference is less. But, 2 high-flow cats would be required to flow more than one 3" high-flow cat - i.e., one high-flow 3" cat will flow more than two factory 2-1/4" cats.

Headers that will bolt in without modification are fewer for dual cats than for single 3" cat. SLP, Edelbrock TES, and Hedman are the only ones of which I am aware that make them for dual cats.

If you go with the Hooker 2055's and want to keep dual cats, you're going to have to modify the y-pipe.

You don't need a 3-wire O2 sensor with these shorty type headers.