Hey Dan,
Don't be mad. Been there done that. You could do a search on this forum and find that a couple of months ago I posted my fisrt dyno results and they were right in line with yours. I was so pissed that I thought I waisted my time and money. Everybody with a KB claimed to have over 400 rwhp. My first dyno showed just 368 rwhp...that's 37 rwhp short off KB's claimed 405 rwhp (as show on their site on a stock GT).
Anyways, your power curve looks very well to me. Here are my insights:
1) It seems like your engine is cutting out well before 6000 rpms. May be your speed/shaft limiter is kicking in. Talk to Ken about it. Mine was kicking in at 5400 rpms and Ken reprogrammed the chip for 6000 rpms. Run it up to 6000 rpms and you will see 390+ rwhp.
2) Was the test run on a dyno jet? Other dynos will show lower numbers!
3) Double check the ignition system. Did you install Denso plugs? What are they gaped at?
4) Do you have the 90mm MAF from KB?
5) Did you scanned the car while making the dyno test? Do you know what the intake and coolant temperature was at the time of the test? It could be that you are running a little hot and the timing is less than optimal (the chip adjusts timing based on intake and coolant temperatures). The hotter the air temperature and coolant, the more timing is pulled out, which translates into less rwhp. They do this for the pump gas setting (Power), otherwise the engine will ping (knock) like a bitch when it gets hot.
The dyno numbers on the KB website are from a run where the spark timing was set at 23 degrees, that is, a cool engine temp (ECT)and cool intake temperature (ACT). On our engines, you can figure about 4 rwhp per degree of spark advance. On my last dyno test, I let the car cool for a while and measured the spark timing at 20 deg and saw 398 rwhp. That is 3 degrees short...I should've seen 410 rwhp (3 deg x 4 rwhp per deg of spark advance = 12 rwhp). On the shootout mode my car spun the dyno at 418 rwhp!!
That is because the chip set the spark timing at 23-24 deg. and leans out the engine a bit.
Putting ice on the manifold and supercharger should help when it's on the dyno. Just watch the timing at WOT and you can tell. If you start the car up cold on the dyno and do a run in the Power mode, you should easily see 390+ rwhp at about 5900 rpms.
6) You really need to install a boost gauge. That's the only way to know that your S/C is pumping 9 psi (the belt could be slipping too!!).
Give Ken a call ASAP to discuss your results. He won't be happy until you're happy!
Hope this information is helpful and don't be dissaponted. Take Care.
Jorge
I'm kind of pissed. Everyone else with the 9psi kit are well over 400. I think its my damn exhaust. thats all we could come up with. My A/F is a SOLID 11.9:1. All I have is Flowmaster 3 chamber weld-in's. I think that its time for the magnapacs and o/r H. I'll post the sheet later. Just got home from the 3 hour drive and had to vent. On a good note, i did put out more HP and TQ then the 10 Zo6's that were there!!! 
