if you are looking for something reliable i would first start off with modifying the engine, you will save alot of money and wind up with as much power as a 7psi~ blower will put out on a stock mustang. I would get a nice cam, ported heads, larger valves, springs, rocker roller, ported and polished upper and lower intake with a dyno tune, you will be looking at 260hp and 250tq frmo this, and if you want to put a blower on later on i would go ahead adn drop a 4.2 crank with forged rods and pistons in it and you can then run 12psi with out any issues every day sho0uld hold up to around 20 psi.