mine is 2.5 also. You have to give it some time for the computer to adjust to it. they say that takes about 500 miles or so. and also you still need to burn the crap out of the muffler also. i hear fiber glass is in there and i heard steel wolh. but there is something in there you burn out. you can smell it. i'm sure you smelled it already. 500 miles and you will def start hearing a diff. i've had mine over a year now and in a year yours will sound the same also
thanks for the complements also bro