Particularly nice to read posts from SR7 owners - mine's a 58 plate.
Renowned as "Mr cautious", before you make any alterations, double check it won't affect the warranty - afterall, you still have 5 years left! I'm rather a novice with cars, and how/what bits may/may not affect engines.
Me, I go for the "quieter the better" angle (it's probably an age thing), and the sound of exhausts mattered to me in my motorbiking days. As an alternative -afterall it could save you time and money- you could always record a Formula 1 on CD and play it on loop