Well how are the mach 1's running so good with just 3.55's in the rear. Im know they have the shaker hood that gives them about 15 to 20 hp 4 cams, but are 3.55's really that good and i believe the 05 mustangs are coming with these gears as well. Most people are saying go with the 4.10's a few are saying go with the 3.73's, but it seems like 4.10's are the most popular. Im not going to run my car at the drag alot though, mostly to school and work. It is the only ride i have, but was thinking of getting a truck to keep the miles down. I only have 19,000 miles on my 02 stang and thats pretty good.Ididn't want to get a supercharger because they are so expensive but with gears, pullies, shifter, headers, and a chip i should be running mid to low 13's i believe.