One post from all the way back on page two by Bill and this most recent one from pgipson strike me as something that maybe everyone should consider about this rule change. I think making it easier for racers to retub a bent car is a good idea because it could save a guy a few bucks. Being able to take a less desirable model and use it to be in a more desirable class also strike me as a good idea. But... it also occurs to me that if it is common knowledge that a certain 'model' car is a superior starting point for a racecar, what is to stop every competitor from making the conversion? Not that it's a bad thing, but could become something that has to be done to be competitive. For instance, say Bill has a Shelby. He states the only difference is a compression bump and bigger front brakes. I'm not familiar with these cars but say for the 110 lbs. difference it turns out the half point of compression and the bigger brakes clearly makes a better race car. Say for instance it is hard to make min. weight with the Charger anyhow. Then every guy with a regular Charger is wanting to convert his to a Shelby. The engines are the same except the pistons (I'm guessing) but to convert the brakes you need the rare Shelby brake backing plates. (hypothetical situation) Shelby backing plates suddenly become very desirable (read expensive). A guy is racing his 'Shelby' and gets hit in the front wheel area breaking his only Shelby backing plate. The car is then side lined until he can find a new one or convert back to a regular Charger. Again... this is a purely hypothetical scenario.
OK... on to pgipson's question. 1.8 miatas turn out to be better racecars at there weight then a 1.6. (or visa versa) Bill's car is somewhat rarer and not many guys race them anyhow, but there are tons of Miatas. Suddenly if you have a earlier 1.6, you are an also ran. Prices for 1.6 cars plunge, can't give them away. Prices for the conversion parts skyrocket. Guys with 1.6s have to pay or be relegated to the back of the pack. A rule designed to make racing cheaper and easier now makes some cars obsolete and others more expensive.
Sorry for the long winded post. These are hypothetic scenarios, so don't consider what I'm saying in a model specific way. Consider that for instance, with the above situation is there a point listing the Shelby and regular Charger on separate spec lines? Same with the 1.6 and 1.8 Miatas? Does this do a disservice to the guy who found a rare model and committed it to racing? Maybe I'm just rambling here, but unintended consequences seem possible.
Andrew Rowe
I'm already out qualifying several of those cars on the grid 
only to be passed later in the race. 
