The 4" has a very,very slightly deeper tone. Hardly discernable.
Also slightly quieter.
That is also how the Rinehart folks described to me when I met them at the Lone Star Rally a couple of weeks ago.
You can't go wrong either way.
You can only go wrong if you choose another brand.
Just my opinion.
Don
Plus one, having had both, I prefer the 4" as more touring friendly and IMO was quite a bit deeper. Performance is identical, they both run the same size baffles
I'm going to replace my slip-ons soon and seriously considering Rineharts. I read all I could about them. But haven't seen anybody make a comparison between the sound and performance of the 3.5 inch and 4.0 inch versions. Has anybody got any input on this? Nobody around here has 4 inch.
FIRST THING I DID TO MY BIKE WAS ADD RINEHART SLIP-ONS BECAUSE DEALERS SUGGESTION. I HAD NEVER HEARD OF 'EM. THEY DO WHAT I WANTED. LOUD, GOOD TONE, LOUD, GOOD CHROME, LOUD, LOOK GOOD, LOUD. WHAT DO I HAVE, 3.5 OR 4.0"? NO WHERE ON BOX OR MUFFLER IS LISTED. WHERE DO YOU MEASURE AND HOW? PLEASE DON'T SEND ME TO PURCHASE A CALIPER !