I had a vague notion of plug-reading from doing it with my goped's single spark plug . I'd tune the carb to what I thought was a good setting, take it for a hard run and check the plug, hope to see a nice brown electrode, not white and lean or black and fouled from running rich. When I pulled my plugs to change them on the dsm, they were white, which seemed consistant with having a failing fuel pump that was probably delivering less fuel than it should have. I just checked them when I pulled them to do a compression test, and they were slightly fouled but not white and lean, although I had been running the car in "slow mode" to avoid breaking various stuff except for a few bursts of speed. I believe that the wally with no aftermarket fpr should have me running rich enough not to worry about leaning out, especially with my limited mods and fairly low (16 psi) boost.