I have an access cab 2008 tacoma, 2.7 4 banger with 265/70 cooper discoverer mud tires installed. I have a K&N cold air intake which helped a little bit. I live in WV.....so I go up and down mountains constantly. My larger tires cause me to not have enough power to make it up these hills and I lose alot of speed. I know I could get a better exhaust system, but anytime you hear the 4 bangers with an exhaust, it sounds like a pissed off bumble bee, or a suped up weedeater. I do NOT want to change the gear ratio either. I would really like to find some sort of computer chip that actually works that changes the mapping in my computer. If anybody, who has a 4 banger.....knows any way to crank out more HP, please let me know.....Thanks.