I switched from a T5 to a C4 and lost lost 1/10th and 2 mph. The car still has a stock NA longblock and was running 13.4 @ 100.98 MPH for the most part. Now it is 13.5 @ 98. I can deal with the 13.5 but for some reason it just bugs me to be under 100 MPH. I am running a 26 inch tall tire with 3.73's. I am at 14 degrees of timing. I am going to bump that up a little. Is anyone running 18 degrees initial on a stock engine? Any suggestions to squeeze a couple MPH's out? I had the interior out of it at the end of last year and was running 12.9 @ 103. (That was in late October in ideal weather. The car was running 13.1 at the beginning of this year with no interior.) I really don't want to gut it again, but I will if I have to.