Anyone Tune, Or have tunes for a 4.3L Vortec in a 2002 GMC SIERRA???

Hey guys, I have a customer with 2002 GMC sierra 1500, with a 4.3L vortec "X Motor"? He just wants to tune it to raise the rpm limit and a little more power for towing, it is a manual trans, None of the aftermarket tuners like superchips, hypertech etc build a tuner for it because its the X Motor?? Just wondering if anyone has tuned one, or if it can be done I guess.. Any advice would be appreciated, I have only tuned duramax, and dont build my own tunes... I guess everyone makes a tuner for the Y motor but wont tune the X
Please Enlighten me lol
Thanks, Mat

You can tune that truck. Its supported. X is the 8th digit in the vin. X means it is a 4.3 V6. Post up the tune file so we can take a look.