A Harley shorty muffler will be the quietest.. it is only mildly louder than stock... (mostly just deeper in tone), very pleasant..
Any muffler that takes packing,.. will burn and blow out that packing in time... and they are usually louder, because the exhaust is not redirected, but simply flows past the sound absorbing material...
The Harley muffler, redirects exhaust through a baffle chamber, much like the stock muffler...
If you are at an elevation less than 3,000ft,... it will make you leaner, and it would be good to rejet... but, some people don't, and just allow the bike to run lean... Rejet isn't as critical with a Harley muffler, as with some other more free flowing mufflers...
Keeping the stock air filter will help...
... but,... rejetting is not that hard...
If the thought of it is just to intimidating... compromise...
Just putting in a #150 main, will make your engine fairly comfortable with a Harley muffler...
That involves, taking off the float bowl (4 screws), removing the old main (one brass screw), and screwing in the new one...
Ta Da!...
As far as the angled pipe... I've never needed it... and I've done several...
... but,.. if you have any trouble, or aren't to good at finessing things to fit,.. an angled pipe can make it easier...
From what you say, and the results you want,... I wouldn't recommend any other muffler than the Harley...
It will be the quietest, and strongest, and will need the least carb tweaking... (possibly none at all). Carb adjustments will just give you a bit better performance, and let the engine run a little cooler...
When shopping for a HD mufler... make sure it has not had the center baffle plate drilled or knocked out... ask the seller or look down the pipe and see if you can see light out the other end... it should look solid black.. air is forced around that plate into the outer chamber,.. that's where the noise reduction comes from...
Blah, blah, blah... I talk a lot... fingers are tired...
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