I have a 94 TT with stock twins, just BPU. Last summer I refreshed my engine to replace all the leaking hoses, gaskets etc. Valve stem seals were the biggie, but there were small leaks everywhere due to rubber hardening etc.
While I was doing the valve stem seals, I also replaced the cams with Kelford T-202C (268/272) and the springs/retainers with Supertech TS1012 dual springs. Titan V2 adjustable cam gears, and they're degreed in just right.
I used to get at least 240 miles to the tank of 93 octane, and sometimes a lot more with just easy highway driving. But now it's down around 200 or so with general around-town driving, short highway stints, and no really hard pulls or anything. At first I thought it was "just that tank" but it's been pretty consistent last few fill-ups. I'm hoping it's the crappy winter gas, but in general the car barely goes out in the cold.
So, do cams have that much of an effect ?