Alright, I almost have my exhaust figured out, but have a couple a questions. I am going with coated 1 5/8" hooker shorties with AIR, and dual hi flo cats, should I get 3 inch cats or 2.5"? Since the collecter is 3" I was going to go 3" all the way back to the muffler as long as the exhaust shop will make me 3" pipes from the collector to the cats. Is that too much for my basically stock engine? Also what cats do I need, two way with that AIR tube right?
Thanks

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90 IROC 5.7l (L98)
ram air, K&N's, air foil,Flows

LIKE A ROC

 

I would go with the 3" all the way back. I think you are supposed to get 3 way converters, but I'm not 100% sure. Other than that, the set-up sounds good.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission with 2.77:1 Rear End

Current Mods: Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip with 160* Thermostat, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET : 14.32 @ 97.7mph
(corrected for elevation)

Soon to come: LT4 HOT Cam, Air Flow Research 190cc Heads, 2800 RPM Stall Converter and SLP 3.70 Rear End Gears.

 

3-way is a regular cat with an air hook up,yes you should run a.i.r headers and 3-way cats,I don't see why you would need two 3" pipes going to the cats,assuming your going into a single 3" anyways,even if your building true duals,you only need 2.5" for each side.I used a 10" piece of my stock a.i.r. tube on the cat(long enough to disipate the heat) and ran a 12" piece of 3/8" fuel hose to connect the "gap" from where it was cut to accomodate the new cat location.it fit over the steel tube so tightly that I did'nt bother with clamps.for the headers I used the stock check valves and 90* L connectors from home depot to rought the new air hoses(you'll see when you install them) I also bought a remanufactured a.i.r. pump for $25,who says muscle car owners don't care about the environment?

 

I was gonna go with 3" pipes to the cats cause the collectors are 3" and the cats are 3", otherwise I'd need reducers after the headers and before the cats.