I'm looking into getting a catco or dynomax cat..which ones better? whats this air tube thing I've heard about on them.. whats it do? also any1 have any part #s for the catco that would fit for my Car?

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1988 Sport Coupe 305 TBI
K&N
Flowmaster exhaust


Daily driver:
1988 K1500 5.7 4x4 shortbed flowmaster cat-back gutted cat.
AOL: RyanNH84

 

AIR tube sends air to the smog pump for some reason or another...cant remember exactly...but it does send air to the smog pump

 

No, the smog pump sends air to the catalytic converter to help it do it's thing better. You have it backwards.

The direct fit part number for your car is PN#4115 (talking about Catco cats). If you wanted a 3", then PN#9118 is the direct fit (well, it'd need some fab work, so it's not really "direct fit"), or you could get the 3" universal and save a few bucks.

 

I think I have 2 1/4 right now...the catco your talking about is 2 1/2 no ?

 

I heard that the AIR tube is there so that unburned fuel in the exhaust can be burned before in the cat before exiting the car (fuel+02+heat = exhaust).
I bought a catco hi flow series converter (3 inch) part number #2607, im going to put it on when i get my TES headers, and hooker cat back next week.

1990 LO3

 

what about if you dont have the smog pump? Does catco or dynomax make a cat that can work without it?

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86 Z28
305TPI
Stock, but with potential!