I have not run the Carnewal but have read up on its as much as I can as I had initial interest. From what I recall, in the range you are referring to ie below 3500 rpm, the Carnewal will not have much of an effect and the anecdotal experiences of some posters seem to be no different to stock. On WOT, it comes alive but so too all other after market exhausts I suspect.
If MOT requirements are not a restriction for you, perhaps take a look at Soul. I'm on stock due to local MOT crap but going by sound clips (debatable) and owner experiences, I'd go Soul if I had no restrictions.
Have fun in the search and let us know what you end up with.
I have carnewal and came from stock, I really like the sound, no drone, people often turn and check out the car then realize is just a Cayman, haha. it does feel less restrictive since once cat is removed (butt dyno) if you are looking for more HP this is probably not the best way since it stays with the stock diameter unless you opt for the R pipes. if you have the extra cash look for a Soul system, probably the best for both sound, no drone and power gains.
The Carnewal is noticeably louder during cold starts and above 3,500 RPM. I'd say mine is a little louder compared to stock below 3,500 but is it significantly different? No. If you're looking to have a quiet experience while just driving around town, it's a great option. No drone during highway cruising and very quiet when driving in 6th at 65 mph.
Hopefully you've seen my video but if not, you can at least hear the cold start difference (didn't record audio while cruising around town).
I've had a Carnewal from Cantrell Motorsports for about four years. It's one of my favorite mods to my 2010 Boxster Base. It kept the basic tone and burble of the factory cans and added a bit more volume. Not intrusive at all at around-town throttle applications, but gives you the sounds you want when you pull hard in first and second. Absolutely no drone whatsoever.