One thing I DO know is that once an aftermarket tune is installed switching between the silver and red keys makes no difference. What I DIDN'T know is that if you go from an aftermarket tune to stock the TracKey tune is still there and the two keys once again are functional. My situation is that I have been running a custom AED tune for the past year and a half. I have no complaints, the car runs great. SOTP is in the "noticeable" category, contrary to the "raped ape" description offered on another forum, confirmed by the 7 hp gain on the AED dyno. From the thousands of forum messages I've read TracKey would also fall under the "noticeable" category with the added benefits of engine braking, two step launch, and modest idle lope. Therefore I have ordered the TK software but it's nice to know if I am totally disappointed I can revert to my AED program.