Quote: Car had 12" turn down extentions, I also when down about 3 jet sizes if i remember right ,Was 1996 I thought it was a wash since the short times where better but lost 1 mph..
Thats strange, I always jet up on a header only car and jet down with exhaust(due to the back pressure)
I was going from OPEN HEADERS TOO FULL EXHAUST!! IS THAT CLEARER!!!
I was only posting my results to help inform the OP, A simple I misunderstood is fine
