Do throttle body spacers work on Jeep Wrangler TJs?

There are some products out there that claim to be able to improve on the already significant engineering that has gone into your motor. The 4.0 engine in the Jeep Wrangler TJ is well known to be a hard engine to get power out of in terms of "bolt-on" modifications. You don't stand to gain any

Throttle Body Spacer For Jeep Grand Cherokee Wrangler TJ 4.0L

1993-1998 Grand Cherokee (ZJ) Throttle Body Spacers

Opinions on aftermarket throttle body?

PQY Throttle Body Spacer Compatible with 91-06 Jeep

Jeep Wrangler Airaid PowerAid Throttle Body Spacer (2007-2017 JK

✿HIGH PERFORMANCE: Designed to enhance off-idle torque from 800 rpm to approximately 3,000 rpm. 1″ thick to provide a smoother, faster and more dense

Throttle Body Spacer Compatible with 91-06 Jeep Wrangler TJ YJ LJ Cherokee XJ 2.5L/4.0L Engine Gas MJ w/Gasket 1 Raise Manifold Carb Red

For Jeep Air Intake Throttle Body Spacer Kit Grand Cherokee

THROTTLE BODY SPACER For JEEP WRANGLER TJ YJ XJ WJ 2.5L 4.0L 1987

Best engine upgrades for the cost?