Thought I should pitch in here, after a funny experience tonight. I have a new shape Milltek cat back, I think it's the resonated version since it's pretty quiet at low speed / low revs. It has a fantastic bassy character though, and gets a lot of compliments - a lot of petrolhead-inclined types ask if it has a V5 engine!
I have heard this "gentleman racer's exhaust" moniker before and had never appreciated it until tonight. I knew it was quiet at low revs, it has presence but not the "OH MY GOD, LOOK AT MY CORSA 1.2L!!!!!" effect that some exhausts have (thank god!). However, I decided to drive with rear windows down tonight instead of the front ones to see if the noise was any better, because it really does sound great, I'm a sad git I know!
Accelerating from 30 to 70mph, the noise was fantastic and above 50mph, pretty damn immense too. However, at 70mph in 6th gear, the noise was sonorous! It was a super-loud "WHUMPWHUMPWHUMP" that sounded not unlike a helicopter hovering about 2 foot overhead, or someone firing a .50cal machine gun in the back seat. Strangely, when the front windows were opened just a smidge, the wind noise seemed to cut the thumping drone immediately. Upon winding them back up, the noise of the exhaust could be heard again. Jesus that thing pumps some decibels under a decent bit of load, talk about a Jekyll and Hyde of the exhaust world! Has anyone else ever experienced this strange effect before?
A drive by from my car at about 60 or 70mph would probably sound amazing, but I had to roll the windows back up eventually, I could feel the pressure of the sound waves pulsing my ear drums to the point of actual pain and discomfort! Sure enough, pulling back into my estate it was as quiet as ever, the perfect gentleman's exhaust for certain!