That is awesome. I can assist with the tuning if you are using a 90-93 Q45 ECU. I've tried the turbo tune Robert made years ago and it didnt' work for me, car would hardly stay running. I've done lot of tuning on mine, expanding the TP scales was a big step. I hit a TP of about 104 @ 8 psi at and above 4K rpm. The stock map only goes up to 72. That means if you don't expand the scales the ECU won't compensate for any additional air over a TP of 72. Obviously there are many other adjustments to be made. I could get you a conservative tune and if you have a Moates Burn 1 and Tunerpro (free) you can fine tune it from there.
As for twin MAFs I think the easiest way would be to run one dummy and one active. You would just do a map trace to see where the TP value was hitting, then adjust the TP scales to match. For this you could probably just leave the TP scales stock and retune the timing and fuel maps to give you the values you want at the new TP value. With my stock MAF I can max it at around 8-10 psi of boost. It goes above 5 volts often and I'm running 8 psi currently.
A company out of Australia has a digital fuel adjuster that will offset the MAF output at your desired setpoints. So, for example, you could offset the output above 4 volts so the actual output above 4 volts would be lower than actual. This way by the time you hit 5 volts on the MAF it's really higher than that. The one thing I want to test is to see of the MAF will even output higher than about 5.15 volts. I do know that the ECU won't recognize anything higher than that. So if the MAF will put out higher voltages it should work great. At 5.5 volts the ECU would see 5 volts, etc.
http://www.jaycar.com.au/produ...D=347
Worth looking in to.