its def fine to run it thru the inside if the car. You will NOT pass tech @ some tracks, but you'll be fine if you're just going to a regular test and tune night. you should definately retard the timing 3-4 degrees, but change the plugs 2 heat ranges cooler than stock, and gap them real close so you get a good burn w/ them. The better the spark the better the fuel will burn, and more power w/ nos. I dont know if you have one, but get a purge kit, b/c they make a HUGE difference on smaller shots like that.