Just installed the spacer and did some around town driving immediately noticed smoother bottom end throttle response, not as jumpy and torquey in stop and go traffic as with other spacers. Today I took a short road trip up into the NC Mountains to Boone, NC typically twisty mountain roads with 3-5 % grades, all uphill going and trip I have made in my jeep many times. I was stunned by the difference in usable power and acceleration in 4'th and 5'th gear from 1800 to 2800 RPM - normally not a strength of a 4.0L engine, usually when your going uphill at 50 mph in 4'th gear in a jeep and you push down on the pedal you can hear the engine get slighltly louder and that is about all that happens. After installing GSP Spacer I can feel actual accerlation !!!  Not V8 type push mind you, but surprising for a 4.0L. I can't recommended  your product highly enough performance wise.
Michael Croft - NC

"WOW !! product works Great !! my kind of folks"
James Sanders - Fort Wayne IN

"Great product, makes my 32's feel like 30's, THANKS!!!!!!!!!"  Erin Walters - Cincinnati,Oh

"Nice equipment - noticeable power increase all
RPM's and all gears"
WIilliam Huntsman  Twin Falls ID

"Unbeleivable product! It really gave my Jeep that
git-up-n-go with a roar."
Jetojeep Products - Lebanon, Pa

"Dont know if I said it before, but this thing rocks"
Sean Bice - Sierra Vista, Az