Had my K-tec stealth for a month now and:
- Pleased with the 'burble' at idle, nice and sporty but subtle enough
- Quiet as my previous OE exhaust on the motorway, except for when under load
- Nice when giving it the beans, not overly loud and not much louder than OE
- Noisy and fairly harsh under low rev acceleration at slow speeds - however, I suspect I have a slight leak on the manifold side of the cat so this may account for some of this
- Mine isn't mounted 'stealth' - despite it being fitted at an independent 'Renaultsport specialist' - you can still see 1/3 of the backbox and that's with a new rear mount that's been packed with copper tubing. Think I'll take it to an exhaust specialist for adjustment.
Happy with it so far, and I think it will be brilliant once I've got the niggles sorted (not K-tec's fault)