Thinking of swapping mufflers but got a question pertaining to my 340

It's going to be a LOT louder.

The first one is called a 3-pass muffler. With a 17 inch case, the actual amount of packing in there totals over 4ft. That is a lot of quieting.
The second is a straight thru, and with a typical 16 inch case, is only 1/3 the length of the Accurate. While this may not equate to 3 times the sound level, it will be very noticeable.

I have a pair if Dynomax turbo 3 pass muffs. 3" in/3"out. No drone. Very good quieting.When I hit the gas they do make a very pleasant racket,all the way to 7000plus Rpm. And when I take them off I don't notice any difference from the engine, other than it sure sounds nasty with just a 230* cam.