I have an '09 Jeep JX Unlimited X. I recently bit the bullet and upgraded the stock wheels and tires (and lift kit). The place that did the work for me recommended that I install a Superchip Flashpaq to adjust the speedometer and transmission shift times due to the increased tire size, so I went with it. To be honest, I didn't do my research on this product and thought it was "simple fix" for those two problems that would arrise with a change in wheel size.
So when I picked up the Jeep of course the new wheels looked great, but the suprise of the day came when I drove it home. I immediately felt the improvement in overall performance from the Flashpaq.
Acceleration was absolutely NOT the standard sluggish Jeep--but much improved. The (automatic) transmission seems to work so much better. Now it's actually a very smooth trannie whereas before, especially on hwy when I need a little extra punch to pass, it was horrible.
Jeeps are known for their off-roading capability, but also the sluggish performance of their V6 engine and auto transmission. We all "live with" the sluggy performance because we "live for" the freedom. I can honestly say that the Flaspaq changes the entire equation! It's no race car, let's be honest. But the Flaspaq really has made a dramatic improvement in my Jeeps all-around on-road performance.