Ok I'm confused, in the first post and such I was under the assumption that you were running a MAF sensor, then a few post up it changes to a MAP sensor? At any rate there are 2 viable answers here, depending on how much money you want to spend. You can either A. Get an SAFC type of device to take care of the karman count problem, or B. you can get a MAP or SD setup. I suggested this to someone else on another thread in here. You can get a LT-1 MAP sensor setup for about 150(Actually you could probably grab the setup out of a jeep or porsche also), the only problem you'll have is that the MAP setup is 12v, whereas you have a 5v system. However this problem can be taken care if with about 2 bucks worth of parts from Radio shack. Speed density will probably run about the same but is a little harder of a junkyard find. I'll have to check around, but I dont think they ever made a MAP sensor that ran on 5 volts...Back to cheap options I'm also a fan of the pressure switch idea. You'll send stock volts to the ecu until enough boost is reached to trigger the switch.