OK OK, I have been watching this for a while and want to finally add my 2c. I have a tb spacer and a "ghetto fab" cold air kit with a K&N filter on my 89 5.8. Have I noticed an increase in how much power or mileage mine gets, probably not however I do know that coupled with the other mods I have, it runs pretty freakin awesome. I have full MSD ignition including wires, cap, rotor, coil and 6A controller, 3" exhaust with Flowmaster muffler and one of the cats cut off. This with my own fabbed intake kit and tb spacer, it runs better and stronger than my buddies 91 that has 60k less miles on it but has same size tires, lift etc. It is WAY faster and WAY more responsive than it was in stock form (granted, my right foot got WAY heavier when I did these upgrades) and that is where I saw most of my increase, in my head.... Now when it comes to buying a cold air for one of these, I would say NO, MAKE YOUR OWN. You can do it for about $40.00 instead of the $240 it would take to order it. TB spacer worth it??? I dont think so, but hey, it was only $35 and worth a try. Ignition worth it?? I say totally. My ride runs smoother and I have the timing advanced about as far as I can get it to squeeze every bit of performance out of it I can and the only way I could do this is with upgraded ignition. Exhaust worth it, OH YEAH, it was totally worth it, everything combined I do believe it is about as much I can get out of this ride without building a motor. I believe that my upgrades worked but I have no dyno numbers to prove it and personally I think that it would take a long time to pay back the investment if you are trying to get tons of mileage out of these types of items but then again, my ride is currently getting 14.5 in town running 33's and a lead gas pedal...