What valves do I need to support my Non-PI Boost application?

You’re going to spend all this money on the rest of the combination, then cheap out when it comes to cylinder heads?!? Those NPI heads are gonna kill you in stock trim. Unported you're not going to see anywhere near 600hp. Heck, 500hp is even going to take some work if you don’t plan on porting the heads.

The blower can only force so much air into the engine before even it is backed up and overcome with restriction. The small ports and shrouded combustion chamber of the stock NPI castings are going to do nothing but bottle neck all of that incoming airflow. It’s not going to take in the amount of air you need and won’t be able to expel the amount it does take in efficiently. Sure you're going to see plenty of boost on the gauge, but you're not going to be turning the kind of power figures you want and you’re going to create a pile of unwanted heat in the process.

If you absolutely must stay with the NPI heads, then have them sent to Renagade Racing to be ported. Swapping out to a set of stock PI valves should do you fine for 600hp, but moving much beyond that and you’ll probably want something a little more durable to take the heat. A good set of custom ground cams is going to be necessary as well. A set of off the shelf bump sticks aren't going to cut the mustard.

Another think to consider is that Kenne Bells new 2.1L compressor is not very well suited for those kinds of power levels, regardless of what Kenne Bell claims in their advertisement. Pushed really hard, you might see it, but you’ll be straining the compressor to the limits and you’ll need to run a steady diet of race fuel to boot. You’d be better off looking around for an old 2.2L Autorotor design, or one of the big bore 2.6L’s to make that kind of power efficiently. If smog control isn’t a problem, you might even consider the Allen Superchargers “Race Kit” that utilizes a Whipple 2300AX as it’s compressor of choice.

Another think I don’t see mention of, is an upgraded fuel system. Don’t think 255lph fuel pump and a Kenne Bell Boost-a-pump is going to get you there. You’ll need to sink a few bucks into that if you expect to make that sort of power without blowing than nice new engine of yours to pieces. Then you’ve got to start thinking about ignition upgrades….

When all is said and done, I hope you do realize you’re looking into the neighbourhood of a $20,000 motor, blower and supporting components combination in order to reliably sustain the kind of power levels you want. Is it really worth that much to you?