I've heard many people talk about porting and polishing their TPI's but try and try again I cant seem to find how much such an operation would cost. Does anyone know how much the average shop would charge to polish the plenum, the runners and the remaining components in the TPI?

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1990 Camaro IROC-Z 305 TPI.

www.geocities.com/camaromandan/home.html (http://www.geocities.com/camaromandan/home.html)

I think its fairly easy to do yourself, just remove the plenum and take a file to the ends of the runner to smooth out the ends where they meet the intake runners on the heads.
I may be wrong, but I think this is pretty much all they do to it.
Buy a book, it should go into detail on how to do it.

I wouldn't just attack your TPI with a file and call it good. You'll probably mess something up. Porting and polishing, when done right, is done with highly abrasive carbide bits and an air powered inline grinder. Or at least around here it is. I would take it to a shop, they will probably port and polish your whole setup for less that $200. Also, as an alternative you could look into some of the options offered by TPI Specialties. Their Big mouth manifold produces great hp and torque. Either way, you'll gain some ponys.

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67-327, 700r4 trans, 9:1 Comp XE268 Cam, Perf. RPM Intake. 750 Holley, Sportsman II Heads, Ceramic coated headers