2 speed tranny w/ 2nd gear as "turbo' ?

[BrianG]

Not an "expert", but here goes...

If you were to gear up first gear, I'd go with something a little less than a normal 2nd gear ratio. I wouldn't gear the 2nd speed too high though or you'll load it too much IMO. That would get rid of your sluggishness you have in 2nd also give you a bit more top end.

Current setup:
First gear is a 2.77:1 ratio.
Second gear is a 1.72:1 ratio.
Diffs are 2.85:1 ratio.
66/16 is 4.125:1 ratio.
First gear total ratio = 32:51
Second gear total ratio = 20.22

So, if you are running 66/16 right now and 2nd feels sluggish, I'd say go up to 66/20.

66/20 in first gear = 26:1
66/20 in second gear = 16:17

As you can see, first gear is now somewhere in between your current first and second which should alleviate your sluggish start in second without unloading the motor much, while second gear is now quite a bit higher for that top speed...