I have a 98 GT 5sp with the regular mods and I have 4.10s in it. Its fun on the street cause it feels like a bigger engine BUT, at the track I run out of rpm before the end of the 1/4. for example... my car needs to be shifted at 5000 and I go through the traps in 4th at 5500. I have tried shifting to 5th but that was a bad idea. you mod motor guys know that they just stop pulling. If I could do it all over I would go with 3.73s. unless you plan a PI motor swap or power adder of some kind. with an auto...id do the 4.10s.