to make a car faster with more power u have to add mass to increase component durability. Wheel bearings, drive shafts and driveline, suspension linkages, body stiffening because of those pilots etc etc. The brakes alone are 20+ kg heavier so consider that in pounds. The extra g's will drive more fluids too, coolant, trans coolers, diff coolers etc etc.
Look at the zl1. Look at the z/28. Look at the z06. Look at the last gt500 shelby. More powerful cars drive mass in most muscle cases since motors are bigger and torque has to be handled.
Finally, the z/28 is so fast because engineers tuned vettes, Vs, 1LEs, ZL1s for years. What did ford tune? First time with MR, first time a serious rear IRS, first time really grippy tires.
Z/28 is about 3850 lbs. That is almost GT PP mustang mass. Best case 350r will be close to that mass and not have the torque. 315 pilots can handle more torque. Also, rear seat delete is silly, u took weight out of worst spot possible. ________