For what your wanting to do... street car/pump gas i wouldn't trust the fuel around here. Your not after every last drop of HP, so to fatten it up a bit will only make it safer. Alot of this is new to you, things can go bad fast. I know cause i've been there, turbos are a shit load of fun but there is alot going on.
Just take a step back and look at what your doing, Sounds like your getting pushed around by your tuner, you NEED to understand what's going on with your car and he NEEDS to take the time for you to know that. Our you need to find someone else to work on your car.
john
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handle every stressful situation like a dog: if you can't eat it or play with it, just pee on it and walk away.