what gears are best for a bolt on car with n2o? I am wanting to do gears soon and will add n2o this winter. will 390s be ok? it will top out at 120 in fourth? will that get me through the 1/4? give me some input.

Eric

 

I was wondering the same thing. I was wanting to go with 4.10's but will be spraying and am afraid they will be too steep. I do not want to have to shift to 5th gear on spray.

 

I have an A4 with 3.73's and spray a 125rwhp shot and I dont run out of gear.

 

Well, if you get your pcm reprogrammed with stock valvetrain you can hit 6400 rpms safely. 6400 rpms with a 4.10 in 4th gear is 119. 6400 rpms with 3.90's in 4th gear is 125. If you ever upgrade the valvetrain and bump it up to 6700 4.10 @6700 will be 125, and 3.90 @ 6700 will be 130. a 119 trap speed should be good for mid 11. 125 should be good for a high to mid 10. More or less it comes down to how fast do you want to run. having the perfect amount of gear is better then having to much. If you get much past 10's you will probably be a stalled auto at that point, not many people can or like to drive a 6 speed car that fast. I think 4.10 will be safe with a bolt on an 100 shot. If your doing like a 200 shot then you might need to go 3.90.

Chris