Currently running with a Blitz Nur spec R (with the bung inserted all the time).
Would it become quieter when fitting an equal length exhaust manifold? or even noisier?

I don't really mind losing that burble but what power gains can I expect from an exhaust manifold? I believe for best torque gains 4-2-1 would be the best, 4-1 is better for high speeds, is that so?

Thanks for any advice on manifold....