How much whp should I expect?
Definitely right on the mark. I have similar mods, a slightly more restrictive exhaust and I'm at 25psi. And I'm pretty sure it's not an "aggressive" tune. I do have head studs though, and I need to get the walbro fuel pump soon.
I highly doubt that. With the stock o2 housing on there, he is not going to make 355+ on a mustang dyno, simple as that. That o2 housing is restricting A LOT.
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Joined: Sep 2007
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From: Cedar City, Utah
UPDATE: Got back from Vegas last weekend. I did some more tuning and went to get the actuator put on. The tuner there did a baseline pull (on a mustang) and the car was at 258 whp. Suck! Anyway, he put on the actuator. It did hold boost a little better. We ruled out any boost leaks. Also, the MBC seemed good. he tuned me a little better and we got it up to 291 whp. Better, but still short of where I should be. He said that I was getting back pressure and he thought it could be a problem with the cat. Then, some other guys pull up after. They've got similar mods, but stock FMIC. Before the tune, they do a pull of 305! Damn I was pissed. What is wrong with my car! Well, today, I went to Tunex to see what they could see with my cat (Cobb high flow cat). Sure enough, they found that i was getting 3 psi back pressure and that's probably fighting the turbo like the guy in Vegas said. So, I put on the Cobb test pipe instead. Tunex found zero back pressure with the test pipe, so they concluded that the Cobb cat was hurting. I drove away and felt a huge difference. I'm off to Vegas again Saturday and we'll see how it does. I'm guessing that was the problem and I'll be around 320 whp on the dyno there. Wish me luck.
