i have a k&n series 77 cai installed on an I-6. i am also planning on installing magnaflow mufflers. with the cai alone there is not much gain noted except that it is louder. unless you have your pcm tuned which i had mine done by westers garage, then you would see the real power of the I-6. difference is like night to day, firmer faster shifts, higher rpm limit, no more speed limiter, reduced torque management, quicker down shift responses, faster acceleration. i got mine done with the 87-91 octane tune.