So besides just cutting the cat off...are there any o2 simulators or anything I need to get...and if I do remove it...I know I'll gain a little HP and TQ...but will I also gain gas mileage...and also what if I went with headers and different exhaust will it improve my gas mileage...or would I be better off just getting a highflow cat...I don't know alot about this stuff so any help would be greatly appreciated...