What should the inlet size of my new muffler be?

My current pipe is 2", my new muffler should have a 2" inlet also right?

A stupid question but I have little experience with exhaust.

How does this muffler look?




Your help is appreciated!

 

I have a 3" inlet 5" disc Superbrapp on the racecar and can say the theory of disc mufflers looks good but simply doesn't work well on a rotary. Our motors have no cylinder head to quiet down exhaust noise and are quite loud. Only way to make a Superbrapp quiet on street is to remove discs and take away hp.

I had a Magnaflow 2.5" straight thru muffler and RB dual presilencers on my 81 and it flowed very well. Got loud over 4k, had to raise voices when talking on the freeway 70mph, and had to lift when cops around. If you're more noise conscious get the 2.5" muffler with offset inlet/outlets. Bending the exhaust flow will make it some quieter.

Or 2" straight thru Magnaflow would be quieter.

Cops in CA are now able to ticket you for 'modified exhaust'. Period. Simple. Been there. got ticketed. Loud cars attract unwanted attention........