After driving the car for a while, and trying to work with the FM guys to tune the ECU my emailing the maps back and forth, I finally got the car on the dyno this weekend for a tuning session. The goal was to maximize mid-range torque and to generally dial the ECU in a bit better than it was right now. It was a Mustang dyno, which I’m told typically reads a little lower (10-20% depending on who you ask) than the more common Dynojet dyno, OTOH, it’s also more accurate.
The result was much, much lower than I was expecting 
The car started the seesion with about 125rwhp, and 125 lbft of Torque. Given the car’s speed (aka the butt dyno), I expected something much higher. On the bright side, it’s good to know that more power will make this thing even wilder, I guess. Ended the day with ~155rwhp and ~150 lbft of torque. Driving home didn’t really give me an opportunity to test the car, so I’ll have to see if I notice any difference in the day-to-day usage.
One major problem we noticed was that the boost from the turbo peaks at around 10.5psi @3500rpm, then starts to droop after that, to about 7.5 psi @6500. The net result is that I’m loosing a bunch of mid- and upper-range power. Probably good for another 20-30 rwhp if I can solve the boost droop. I think the problem is likely my exhaust, since it’s basically a thrown-together custom job that I had done without the guy being able to see my car, so there are several tight bends and restrictive points that are probably creating back pressure, which would prevent the turbine from spinning up properly.
All in all a very educational experience, and the next time I do one of these, I hope I’ll have fixed the boost droop, and possibly changed the cam timings a little.
