Yaris VS MX5 showdown

[Jason@SportsCar]

Originally Posted by ivanstepul

I dont understand the stf es or cs business. Are those different classes? Im just trying to put up a faster time and do whatever it takes. The 17 that I have are heavier than the 15 inch wheels i have but i have wider tires on the 17s i feel like i have more grip with those wheels tires. The tires that I'm currently running are GT Radial Champiro UHP1 205 /45 R17 88W XL BSW.

Those are SCCA Solo classes - this match up you seek is played out every weekend around the cournty... A Yaris modded like your list, less the interior removal, would be in STF. Stockish Miatas are in CS and ES, both of which are quicker. The Miata has more power (even after your mods), less weight, RWD, and way better suspension. End game.

You accomplished nothing by going to a 17" other than aesthetics. Same width 15" wheel/combo will beat the 17" every time, the 15" carries less weight and offers a gearing advantage.