The reflash should be a qiuck turn-around. It should not affect the warranty unless it could be proven that the reflash caused the problem. Two camps on the flies and the TC. One says it does affect TC and one says it doesn't matter. I guess that depends on whose arguement you like better.I personally don't think you'll need a PC5 unless you install a catless full exhaust system that actually increases in/out volume of airflow.