in additioin to the other upgrades installed
The Jet Power-flow spacer has helped the other engine upgrades that I have installed. These include a PCM of NC performance PCM, Jet Power MASS sensor and a Volant Cold air intake that connects directly to the throttle body. I'm not sure of the total HP/ torque increase, but this upgrades have made the 4.2L perform like a V-8 and has given a consistent 20MPG on the highway (highest was 23MPG on the highway) which is better than the 17MPG that I was getting in stock form.
Just what I needed...
I'd added a K&N FIPK, a JET Throttle body spacer, JET Performance module and a Flowmaster muffler to my Trailblazer and still was missing the OOMPH. My wife ordered the JET M.A.F. for me and that was just what I needed! The truck has great pick up and sustainable power. The throttle response is also greatly improved. I'd recommend it to anyone with the same or similar vehicle. Thank you JET Performance.