Do gears put more stress on your engine and tranny? I was thinking 4.10's but I was wondering if the higher revs on the highway would prematurely kill my tranny and engine. Also, is it true that I'd lose overdrive with 4.10s?
I do not know that driving at a higher RPM such as 3,000 will kill your engine. The mazda protege that I drove for years spent most of its time on the highway commuting to work and home from college on weekends, cruising at ~3,500 rpm going 80mph and that thing has over 100k and runs fine.
Will you lose overdrive with 4.10's? No. Your transmission will still be in overdrive, you're simply changing the gear multiplication at the rear diff. FWIW, I'm seriously considering 4.30's for when I get gears.
I have an 04 GT with 4.10's and I love em to death!
5th gear is useable now. At 70mph in 5th gear you'll be at ~2500rpm which isn't all tha bad. I did notice a 2-3mpg drop though. The main problem is keeping your foot off the gas, it feels so darn good!
i would say it does not put more strain on the tranny(unless its a auto where constant rpm's make more heat which kills autos) or motor, and id even venture to say it puts less strain on said parts. gears are a torque multiplier, so in essence the taller the gear, the lighter the car "feels" to the motor and tranny.