Looking to put a 408 stroker kit with short tube headers and 1.7 rockers inside my engine. Stock cam, stock heads, and stock intake and injection system. Will I need to tube the truck for it to be safe to drive? I'm looking for maximum fuel economy with this setup so would the old tune work? And yes I know I'm not looking for better fuel economy than before I just want a little more get up and go without diving my fuel economy into the single digits. I currently get around 16mpg if I maintain 60-65mph

 

"better fuel economy" and "408" don't really go together. If you are gentle you might get real lucky, and stay about the same, more likely though, you'll drop a couple points. For it to run properly, you WILL need a tune. How easy that is depends on what year your truck is. 96 or new, you can get a custom tune, and reflash the PCM, 95 and older though, that won't work...... as they are not flash programmable. Your options are pretty limited there...

 

I think a turbo or two would give you what you are looking for as long as you can keep your foot out of it. Larger displacement needs more fuel to run even if you drive normal.