Yeah I'll just change the speedo gear

you will then however have trouble hitting the rev limiter before gear changes.

ecu is coded for the 3.08/3.23 or 3.45 diff wasnt it?

so your ecu will want to change at say 80km/h in first. however you new diff will only allow 65, then your going to have trouble.

thats what i was thinking

if you fit the jaycar speedo corrector in the trans loom before it gets to the ECU, you shouldnt have a prob, as the revs will be higher than the speed at which you were previously doing.

Ive got 3.7's in mine and Ive noticed no difference in fuel consumption, however mine is driven flat out most of the time no matter what ratio, so I guess thats why I havnt noticed any difference.