I have some time on my hands (winter), and since my car is hibernating (winter), I thought I would give this a try. Is it a straight-forward procedure, and is it worth it from a performance standpoint? I could go with aftermarket stuff, but I want to retain the stock look.

Thanks
'90 IROC, 5.7

 

Go for it bro. You'll notice a difference. Most report a tenth of a second off the 1/4.

Just get a Dremel and buy those cone shaped grinding pieces. Theyre like $5 for a couple of them. Get a few drum sanders too. Make sure you get enough to do the job.

Just take down the wall behind the opening and radius in the walls. Be careful not to go through.

When you do the runners...take the runner gasket and put it up against the plenum. Trace around it. Now you will grind only to those circles. This is called port matching. Do it to all 8 runner exits.

While you have the time, you may want to consider the addition of a adjustable fuel pressure regulator. Crane sells one for $66.

If you really have time yank the intake manifold off and port match that also.

Good luck.

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'92 Formula
305 TPI 5speed
1LE package
Mods: SLP headers,SLP catback,SLP air foil,ported plenum,Crane AFPR (42psi),MSD6AL,AC delco cold plugs, Bosch O2sensor, homemade cold air,K&Ns,3:73s,JET fan switch, Macewen white face gauges...Comp cam (i still have to install it )

 

Definitely worth it if you want to retain the factory look. In addition to the plenum mods, grind the ridge inside the runner tubes where they join to the runner flanges top and bottom. Pretty easy with a dremel and the sanding drums. The stock lower intake base is pretty restrictive so if you don't want to aftermarket, hand port it or have it extrude honed.

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89 Formula 350, Accel Tri-Ys, 3" SLP, chip, Jacobs, SLP cold air, Probuilt tranny, Vigilante, 3.27s, Spohn torque arm & LCAs w/brackets, GW Subs

 

Basically, you will feel awesome throttle response and the car will be "quicker">>> meaning peppier and much more responsive. 1/4 mile times won't be affected so much. IT is definetly worth it though

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Alex (AKA chevyboy) '91 RS 327 stroker, trans-go shift kit>> manual valve body, cat-delete, MSD (ignition, coil, 2-step, timing retard/ advance),Flowmaster, complete Edelbrock suspension including shocks, struts and lowering springs. CRAGAR drag wheels. Lowered 2.25" in front and 1.5" in rear....Best E/T 12.84 @109 mph...(got spray?)plus more!!

 

With the addition of a 52mm TB, ported plenum, and a ported base I picked up .2 and 2 mph. So yes, it is worth it.

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Jason D.
92 Z28