3.25 sounds fine to me then, its not a HUGE step like other people choose. If your only on the freeway twice a day for a short period of time then it shouldnt worry the old hip pocket. If however you make trips up north or down south a fair bit then it might cost a few extra dollars.
With that said though, running your engine at slightly higher revs wont use much more fuel. Your smack bang on/in your torque range, so the cars doesnt have to work to overtake or just speed up slightly. I can see it being more effiecient. Ive tested the fuel economy at 100 and that read 8.0L/100km, and i tested it at 150, and that reported 10.0L/100km. So i was getting 50km further & quicker for only 2L more fuel usage, which is a shit load more economical, and that due to me sitting smack bang in the middle of the torque curve.
Theres more to it than that, but yeah, go for it, have some fun :D