It sounds like you went into limp mode. There are a number of possibilities but you will need to have the dealer read the codes. Here's the rub - with your down pipe it is likely they will blame that for the limp mode (not an unrealistic explanation) and flag your car for warranty purposes. I wouldn't take it in unless it happens again. If it does, I would take the dp off and see if you can recreate the issue.
What octane gas are you running? Which brand of gas? What was the ambient temperature?