Had one installed on the wife's Coupe - she hated it - too noisy. So when my Cabriolet arrived, I had the dealer swap the DTH from her Coupe to my Cab. I love it! Sound is a bit throaty and can drone a bit, but the performance improvement is, IMHO, quite noticeable. Give the engine management ~500 miles of *mixed* driving to get used to the freer flow - you'll hear a bit mellower sound and a more consistent, improved performance; especially acceleration. It won't turn a Smart into a F1 machine, but when you start with as few horsies as we have, it doesn't take much to show a tangible improvement!
Cheers,
Jeff