Originally Posted by fuelmoto

If tested on the same bike with the same headpipe and mods a 3.5" and 4" muffler will sound the same if they have the same core, there is only a .25 difference in air gap between the muffler body between them. This is something we have tested extensively with both dB equipment and on-road testing. Mufflers also sound different with the "new style" OEM 2/1/2 headpipes compared to the earlier headpipe, and the 2010/2011 catalyst headpipes sound different yet as the catalyst suppresses sound by as much as 2-3 dB.

As a side note when comparing the Rinehart slip ons, it is important to note there have been significant changes in the internals over the years. The previous Rinehart by Bub mufflers had several baffle variations over the years, while the current Rinehart mufflers produced by Clearline Inc have all used the same 2.25 cores in their 3.5" and 4" mufflers. Overall while they have changed, they have all sounded and performed well

Originally Posted by azbob09

Jamie, You & Fuelmoto have such a good reputation on the forum that I've got a couple more questions.
Can't you get the 4" rineharts slip ons with I believe 3 different baffles, like your 4" dyno tuned slip ones? Also, if you put either one of these two mufflers (with standard or high flow baffles) on a 2011 103" limited & left the cat header & a/c stock do you feel it could still possible need a tuner? Particularly if you ride in 105+deg heat like in Az. Thanks for your time...