If you're going to buy a TB spacer at all, get the cheapest one you can find (or make your own) that has a 62mm bore and no helix. That helix bore is nothing more than a marketing gimmick so don't fall for it.
If you then add a 62mm TB (cheap in ebay), a true cold air intake with the filter shielded from hot underhood air (you can make your own with bits bought from Home Depot), and insulate the underside of the intake manifold with a Thermotec heat blanket, you'll see a nice improvement in throttle response and a slight improvement in gas mileage.
With the intake side of the engine taken care of, it'll then respond better to a freer flowing exhaust.