These are the top 5 HP numbers people have gotten out of the M90 on this cam. It's not as easy as it looks though, realisticly, you will probably make 50-70whp less than what these guys pulled off.
ZZP's Comp Cam XPZ grind:
1. Zooomer w/ 464WHP (I/C, G5 m-90, ZZP Alum Heads, 10.5:1) [STD / Mustang Dyno]
2. Scott Kleis w/ 425WHP (I/C, G5 m-90, ZZP Alum Heads, 9:5:1) [STD]
3. Fred Cakanic w/ 421WHP (I/C, G5 m-90, ZZP S3 Heads, 9.5:1) [STD]
4. ALancour w/ 400WHP (I/C, G5 m-90, ZZP Alum Heads 10:1) [SAE / Mustang Dyno]
5. House w/ 393WHP (non-I/C, G5 m-90, ZZP S4 Alum Heads, 1.7 rockers)
Honestly, if you are going for WHP you should really be looking at turbo.
The other problem with a 400whp XPZ grand prix, the drivability suffers, your powerband will be shifted so high that the car will be a pooch anywhere but WOT. At that point, 400whp on a fwd grand prix is kinda useless. You have to realize that the car is not going to drive around like it used to. There are a lot of people that go "all out" only to demod or sell it weeks later.
If you can put the power to the ground and lose some weight, low 11's are possible. With something like a S1X cam or XP, low 12's are possible.
