I have been down this lonely road with the returnless. Its a bitch. Steeda is making a system to convert it return style and Aeromotive has a set up now too. I am running Aeromotive set up on my car, it can handle 1000hp.
Prior I had a 255 pump and 30lbs injectors and putting out 350whp and it was running lean. Tried tuning it with a chip and that didn't work out all that well. Then went to 42lbs injectors it worked pretty well, untill I started putting 12# of boost in the motor and bumped up the timing.
But as far as blower application all the kits provide you with what you need for your motor to handle the power, as soon as you start going over what comes with the stock kit, have fun.