Matt, I had a chance to see a SH .28 Pro in my IGT over september fest, it was off the hook. WAY too much motor, even with GRP med. compound tires. Engine runs about $130 from RCmart.com rcMart.com by Dinball - Your RC SuperStore :: SH Engines (#PT2803ACP6) 28 Pro Rear Exhaust Engine

If you are looking for something slightly more controllable but still cheap I recommend a Hyper .21 Pro for about $135. Its not just a "pro" tag, the piston, sleeve, conrod, and crank are all different. Much better performance over a standard 8port. Though not quite up to a Vspec, P5x, or any other on-road built .21.

VERY Fast acceleration. An easy 50mph in the 110ft straight we had. Brake upgrade is a must though, I was overheating the stock disc within 1 or 2 hard stops and it would take at least 15 minutes to cool it off. Buy a fibre disc or go to a dual vented metal disk.