can you change gear ratios in a lexus is 2006+?, and if so will it affect the cruise when changing the 6th gear ratio like, maybe not being able to stay in the speed i selected, because i hear thats the gear the car uses when cruising, I've searched a lot and can't find anything related.

 

I'm unsure of the question you are asking.

You want to change the gear ratio inside the transmission? Or the rear end?

For what intended purposes?

 

from what i understand of gear ratios, the higher the number, the more acceleration but lower speed you get, starting from gear third the is350 acceleration drops badly so i though maybe because of a larger gap in the gear ration in an is350, and i also hear that the is350 can reach its top speed in 5th gear, and sixth gear is just for cruising and even though the engine is capable of going more than 145mph lexus put a speed limiter , so what i had in mind is to change the gear ratios to where it would reach its top speed of 145mph in 6th gear instead of 5th by lowering gear ratios a bit, that would definitely increase acceleration without losing speed, even though mpg is going to be affected but oh well, sorry i don't really understand much about gear ratios i just started researching about them, I'm not sure about inside transmission or rear end, i only know little things about gear ratios, so correct me if I'm wrong.

 

The ONLY known option (if you have an IS350) is using an IS-F pinion and matching ring gear in the rear end. That'll net you better cruising rpms...if that's what you're after. But honestly, if you're after MAX acceleration, the IS350 already has the best ratio for that.

Check this video out with an IS-F owner with a before and after AFTER installing an IS350 pinion and ring gear :