Hello, i have a 99 f-250 with the 5.4 v-8. I have recently Diablo Sport chipped, K&N filter charge and straiht piped it. The problem is after all of these modifications its still slow. It wont break loose on corners nor will it at a stand still. I understand that i purchased a truck i know that but when you see the same truck with the same engin kicking your butt with no mods theres somehting wrong. Im not the only one with this problem either. After tlaking to a few buddies i heard a rumore of mid year ford switching ou the plenum, located on the top of the engin, also has the fuel rail atatched to it. Does anybody know where i can get a performance rail? or anyhting i can do to the truck that i havent already. Im want to do things that will help me out possibly find a whole new engine without acually spending the few thousand for a supercharger. I 4x4 and i dotn think a SC is a good idea. Thanks for your time and i look foward to hearing back from you.

 

Is there a chance since you straight piped the exsaust you might have lost you low-end grunt by removing to much back pressure

 

Thats what i was thinking.

Rand