well when you re-jetted and dialed in your timing, you were basically tuning your old stang. since all modern cars are fuel injection (computer controlled) and no longer carbuerators, you need a "computer" device such as a tuner to modify how much fuel and air is getting to your engine. of course there are many more adjustments you can make with a tuner but maybe you now get the idea. adjustments are no longer ONLY modified with hand tools like the old days. computers are already the standard. i remember when i first got my stang and was programing it with my tuner and my pops was like, "what the hell are you doing?!, going on the internet!?"...hahaha, i explained to him how new cars are tuned this way ( he still drove a '63 ford ranchero) and he was like "ooohhh". basically, trust us. a tuner will do your new stang lots of good. SCT and Diablo tuners come with three standard tunes pre-installed. i know the diablo comes with a performance tune for the different octanes available at the pump. although these tunes improve you cars performance over the factory settings, they are not the best. they are created without factoring any other mods. custom tunes that you purchase factor in the mods that you do have (cold air intake for example) and take full advantage of these new parts. hope this info helps.

 

Thanks for the feedback. That's the kind ofinfo that helps make these forums work. It seems like the SCT tuner is the most popular.