My brother whent from a 3.73 open diff. to a 4.10 possi. and his mods where: JbA headers, K&N Intake, Ls1 fans, ASP under drive pulley, Shift kit, servo, Tb spacer. I believe that was all, his 1/4 mile time with the 3.73's was 14.89, with the gear swap 4.10's was 14.64. With the same tires "stock". And I'm minutes' away from swaping my 3.42's on 2004 gmc 5.3 to 4.10's. As soon as I get them in there I'll let you guy's know what my change was.

 

Oh and he also had a Borla exhaust.