ive got a powerchip gold in my car atm.
the difference is noticeable, but not to a huge extent.
it seems to pull alot harder from 1500rpm to 4000rpm (due to the sliightly increased torque). a few weeks later my car started to run like shit. after checking ecu codes (suspecting the tfi module), turned out to be o2 sensors(which generally tend to **** up after 160,000kays. so they were due to go).
Now its all running shmick, when i change cams i might get a uni chip, however the stardard ecu is programable with the right tools.