Techron is good.. I've seen the results first hand tearing down a 911 motor that I ran Techron through with every oil change.
HOWEVER.. I have seen a more direct improvement in my Jeep and my 951 using the Lucas products. I highly recommend the Lucas fuel additive (
http://lucasoil.hodgsoncorp.com/lucas_fuel_treatment.htm
It solved a bouncing idle issue in my Jeep, and marginally improved throttle response in the Boxster.