I think the numbers y'all figuring are a little low:
http://www.e90post.com/forums/showpo...postcount=1226
+78whp/340whp on a Mustang Dyno from Helix alone.
Here's a helix dyno with DPs and FMIC:
http://img2.putfile.com/main/3/6015523886.jpg
+106hp/ 387 whp with stock intake and exhaust, on 93 octane.
I'd imagine that setup could hit 400whp with a DP-back exhaust that deleted second cats, and a higher flowing intake system.
Generally speaking, on these cars, race gas is good for another 20-30 whp. The engine will use it's own logic to add timing up top with the addition of race gas.
PS: No reports of tranny exploding.