ok i am trying to see what works and whats the best all around setup. i am having a motor BUILT for me. BUILT meaning done to the hilt so i dont have to ever do anything else to it. i am the type of guy that overbuilds for future use. i want something in the area of good mpg's and if i want to open up a can of whoopa$$ i can just turn the knob. i wont ever be towing anything heavy just the family boat 5k. this is going into the x and not my truck. really looking for everyones opinions. i know that 238/80's are highly talked about. lets say if 300's were thought of can it be turned down to still get mpg's or no? 238's are said to be great for mpg's but good to what hp? all the info would be greatly appreciated. dont forget let's try to match injectors with what turbo. dd is what this would be for.