you know, me and a friend have both noticed something rather interesting out about our 3.4s. he has a '95 tacoma, with a supercharger. we both are using cone filter intakes, his is a full k&n and mine is just a k&n cone filter. we have both noticed that there is a certin point in the throttle that causes a slight whistle. it seems to be right after you crack the throttle. we noticed that on the supercharged tacoma, this whistle is right at 0 psi on the boost gauge, as in no longer in vacuum, but not completly boosting. at this point and lower seems to be where i get the best milage. with the throttle body spacer, this sound is louder, so i can really tell where it is.