I have both, a Renntech ECU & pulley kit and a Sprint Booster on my SRT6. But I can't really give much input on the Sprint Booster because I installed the Renntech kit before I drove the car with just the Sprint Booster. But I can give you input on a Renntech kit, AWESOME! I gave a friend a ride in the SRT6 yesterday and he was amazed, he said "man, this thing would eat-up a Vette".