I've not signed it. And I won't.
Nothing will ever get put into legislation to help us: It's simply not a vote winner. Ever. The best thing we can do is to help ourselves, and stop giving them a reason to complain. Every time someone does a trackday with an exhaust that they think may or may not be quiet enough, that's working against our cause. Every time someone thinks that track day = drift day and spends all Saturday with tyres singing, that's working against our cause.
I like loud exhausts. I like sliding on track. I also know when taking the p*ss is going that little bit too far. If every single trackdayer stopped chasing every last bhp and instead made a hugely concerted effort into making their car as quiet as possible, we'd all be winners. Stop giving the NIMBYs ammo and they'll go complain about something else. My track car is massively quieter than our road car (MR2 vs Mini), and even when I took the 911 on track I left the exhaust in quiet mode as there was no point wasting dB.
Sure, loud cars are fun and I won't pretend they're not, but ultimately driving cars is more fun than listening to them. We should help ourselves on this, because you can be damn sure no-one else will.