my 1-2 shift is at 40 mph on 3.42s
is your tire size correct that could be throwing off the speedo?
you did go to a shorter tire meaning its turning more revolutions per mile if it isnt right thats your reason for the new found 55 mph shift

Yes 4.10s are nice but i dont wanna loose mph thats my hold up,i tend to play on the street some and mph is good
I am sure it will drop my 60ft times and pull a good number at the track
Also my fuel economy is good !

 

well my tire size was rt before and it was shifting at 55 when tune said it should b at 40 thats y tuner said my tranny was slipping. but rt now its off so i would understand y it says im shifting at 52 which is like 45 due to the tire size difference i will get that adjusted soon.. im going to get a shift kit installed to c if that fixes the problem.. and does anyone here tune? i bought my vin on efi live so i can make changes like tire size when i need it but i also have to adjust speed it shifts at to match with rpm.. and i dont know how. is their anyone that knows how to match up rmp with mph? is their a formula needed? thanks..