how would a pair of performer edelbrock cyl heads help my 90 IROC's 305 TPI motor out, its got a 150 shot of nitrous, runners, and a cheesy dynomax performance muffler, would it be beneficial without headers, and would l actually feel a difference, what comes first heads or headers?

specs on heads:60 cc ports with centerbolt mounts- emissions legal 2.02/1.60 intake exh valves will anything else have to be replaced other than heads? will it work with ECM?

thanks in advance

 

Why not do them at the same time? Probably make the header install a little easier. Seriously, if you were gonna do one or the other first, go with the headers first.

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L98, 3.27 9-bolt, Hooker shorty headers, custom 2.5inch Y-pipe, no cat, 3inch 2chamber flowmaster, JET AFPR, Ported MAF, Best ET: 13.86 @100mph. 1.99 60'
17 inch ROH "ZS" wheels. 17x8.5(front) and 17x9.5 (rear). Firestone Firehawk SZ50s. 245/45/zr17s and 275/40/zr17s. T56

On the way... Radar Blue 89 Formula, T56, Ram Jet 430, Ram Air, 17inch ROHs.

 

I've heard the large valves won't work with the small bore 305.

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1989 Trans Am, 305 TPI 5-speed, T-Tops(love 'em),4-wheel disc, 3.73 posi(the toy). '97 Camaro V-6 T-Tops(daily driver)

 

really? l don't see why not though

 

Yea, he is right. Edelbrocks with 2.02 and 1.60 wont work on a 305.