Your best bet is some Porsche specific ones, 102dB is pretty punchy.
It's almost silent at cruise, barks a bit on start-up but idle is very quiet - it's only at high RPM that it starts to get a bit shouty. 102Db is quite shouty, I admit.
I've emailed a couple of places about getting Porsche specific ones.
All the car's i've built have to go through MSA noise test at scruiteneering, we always struggled with the test protocol and rear engine'd cars specifically.
It's almost silent at cruise, barks a bit on start-up but idle is very quiet - it's only at high RPM that it starts to get a bit shouty. 102Db is quite shouty, I admit.
I've emailed a couple of places about getting Porsche specific ones.