As I suspect occurs in all classes/categories, we have the same type of constant discussion in GTA as well. One guy even went so far as to post that, in his twenty years of circle track racing, he's figured out there are two types of racer - cheaters and losers! The guys at the back invariably complain about the guys at the front cheating - did I mention this guy is generally toward the rearmost portion of the grid?
My standard answer to those types of statements is, "If you plan to run at the back then run whatever you want because nobody cares. If you plan to run at the front, however, you'd better damn sure be legal!"
Another buddy is Chief of Tech for one of the semi-pro road racing series, and they do regular inspections of the top three finishers plus a random check of others throughout the 30+ car field. He says the guys at the front are spot on the limit of the rules while most infractions they find are on those randomly chosen from the mid-pack back. That is supported by the recent GRM article (which I thought was very good) on "Pros vs. Shmoes". That article was dealing with Spec Miatas, but could well have been written about ANY class in ANY form of racing.
And when people think I'm cheating, I smile and take it as a compliment. It also means I've got them where I want them - thinking about MY car rather than trying to figure out how to improve THEIR car and driving.