i'm running the rectangular header. the lrp is a side exhaust. i've had the motor in the truck for almost two years now. i bought a factory team header for it and just took a little time to port it. everything works great. I only bash with the truck, and its got more then enough power. Not to say that you wouldn't be happy with an OS. i've just personally been a fan of the lrp motors and had great luck with it. From what i hear though, i'm sure the OS would be a great little powerhouse for you also.