I had one in my jeep and it was okay.. I would not say it's worth the money i paid for it .. But it helped some when i added the a free flow cold air intake and filter, way biggger exhaust with higher power coil and bigger gapped spark plug and i played with the timing to help make performance.I had 8.8mm spark plug wires and put in a high flow cat with a flowmaster 40 with 2 chambers...
A throttle body spacer is usually a 1 inch thick piece of metal that is bolted to the back of the throttle body downstream of air flow into the manifold. By changing the airflow, this after-market add-on does claim to be a performance enhancing accessory that can increase an engine's horse power, torque and fuel economy. It functions by swirling or directing the air flow to maximize air volume to the manifold.