Another problem

[ringman]

It seems like when I fix one problem two more occur. I just had several things fixed on my car at Aggressive Perf. They seemed to do a good job for a decent price. Anyways, the car was running well, and now for some reason on the highway when Iam de-accelerating the car backfires. Normal driving it is fine, only at highway speeds when I slow down it backfires. Also, I can't get more than 17psi of boost. Wastegate is maxed out, and even with the vacuum line off it won't go past 17psi. Is my wastegate bad?

THanks in advance for the help

 

[ES1]

Do you have any scantool readings?
Do you have octane to push past 17psi?
You might try shorting the rod some to get more boost.

 

[ringman]

I use turbolink, I have no readings yet, tomorrow night I will hook up. I am running 110 octane right now. I have a gas station a few miles from my house that sells it for $2.73 a gallon, which is 20 cents cheaper than premium.