I have to admit most of my war chest in in body mods. The few and I mean few things you can do is...Switch out your air filter, Bore the TB, and nitrous injection. I spent months now up long nites scouring web sites and forums, and have had a couple in depth discussions with a local service mananger who is a leader in dirt tracking around here. One item I havent done that might be worthy is to locate unworn, undamaged STS heads, that would add the 25Hp lost in the STS trade.
The PCM cant be reflashed. I mentioned somebody will eventually crack the codes to the service manager and he said aint gonna happen. I forgot the term he used for our PCM, I'll ask him again whenever my dam wire harness for fog lamps gets here( I think their making the things one at a time
The flow is already tuned well for OEM and I wouldnt put steel headers against these aluminum heads(especially with the added heat of nitrous) the block and heads are cast using a "squeeze process" that left them unexpectedly porous and I have read more than one account that the average of a half a quart of oil missing each oil change may be seeping into the block.(god knows what that will do over time.)
The Valves can NOT be altered. The valve seats and guides are power coated at Northstar and cant be redone. The valve drain depends on tolerances set for this powder coating. They are throwaway heads and if you damage one one valve, the only fix is replacement. This is true of the bottom end also where thin steel sleeves are used in the cast process of block and cant be rebored. Getting depressing isnt it.
Nitrous IS on demand, if your fittings are all tight and you check them well for leaks you can leave bottle on without worrying about leaking. I leave mine on all the time.;when car is running. yhere is a arm switch with Zex but the valves work when you WOT and close as you let up on throttle. Zex chip knows exact throttle posiition by means of a wire that ties into TPS switch. The other info is in the Nitrous threadhttp://www.bonnevilleclub.com/forum/viewtopic.php?t=52111