Check your spark plugs and gap them to .030 and pressure check for boost leaks first. Boost will blow the spark out on bad or high gap plugs. Small boost leaks at high psi can open and cause breaking up. $650 for a rom tune at XAT Racing. A ball bearing t28 @13 psi can put you past the 250hp mark; where you start to need some kind of tuning, injector upgrade, as well as mass air flow sensor upgrade like a z32 mafs. You cant run that much boost safely without those mods. As for the intermittent smoke, that could be turbo, head gasket, etc. Get it checked out.