I am very pleased with this MagnaFlow muffler on my 2016 3.5-liter V6 3rd gen Triple T/Case Toyota Tacoma Rock Crawler.I wanted something that would outflow the stock system but would not be too loud as I drive long distances to-and-from trails as well as daily drive my Tacoma. For example, I live in Central California, and have taken my Tacoma through the Rubicon (NorCal) twice, the Hammers (SoCal) once, Moab (Utah) three times, trails in Colorado once, and trails in Texas twice. Just in the past month I've driven the Tacoma 5,600 miles to trails in both Texas and Utah on two different trips.The factory Toyota 3.5-liter exhaust consisted of 45mm (1.77") inner diameter (ID) pipes between the cats and Y-pipe upstream from the muffler, and after the Y-pipe is 57mm (2.24") ID pipes both in and out of the stock muffler. *Note: Even though the driver side cross-over pipe measures almost 2.5" OD, it is a double pipe: There is a smaller 45mm/1.77" pipe within it!!Many people on forums seem hell-bent on running 3" exhaust (76mm!! which is 5.7-times more flow before the muffler holy crap!!), but, if you consider how small the stock exhaust is, this 12580 Magnaflow muffler positioned "backwards" in dual 2.25-inch inlets and single 2.5-inch outlet is a great upgrade: 123% or 3.2-times better flow between cat and muffler, and 25% or 1.25-times better flow out the muffler. Then, combined with the fact the muffler itself is free-flowing, even this "small" 12580 Magnaflow is a huge increase in airflow over stock.One other thing to note is that the diagram on Magnaflow's product website of the internal Y-Pipe is INCORRECT. It shows the Y-Pipe positioned directly at the two outlets/inlets, however, this 12580 muffler actually has the Y-Pipe positioned directly at the single outlet/inlet. So in reality there are two long internal pipes that cover the majority of the distance of the muffler that are collected right before the single outlet/inlet. To me this is significant because if you look at the product photo on Magnaflow's website, I was expecting there to be more sound deadening material due to only have 1 pipe traveling through the bulk of the muffler, but instead there is less space for sound deadening due to the fact that there are two pipes traveling through the bulk of the muffler. Magnaflow: Please update your cut-away diagram!The sound at 70 MPH highway cruise is only slightly louder than stock which I am very pleased with. It has a nice slight rumble off idle and above 4K RPM, and often has that awesome popping sound during long in-gear deceleration (my truck is a 6MT). It also has a nice mellow rumble to it during the high idle moments of a cold-start. For Rock Crawling where you are idling without using hardly any throttle for most of the trail (this only applies to rigs with a Marlin Crawler installed), it sounds great because of the nice low speed rumble it has right off idle. I cannot praise this muffler enough for a combination of daily driving and long trail Rock Crawling while not having your ears droned out for hours and hours, yet it outflows the stock exhaust picking up some MPG and acceleration along the way.Gas mileage has gone up however it's difficult to say how much of the improvement was from either the muffler or my 40" tires. I am currently averaging just over 17 MPG with 40" tires, 5.29:1 R&P, and Triple Marlin Crawler Transfer Cases.Acceleration has certainly improved, especially in the top end.I now have over 7,000 miles on the Magnaflow 12580 muffler and it's been great. Sound has not changed and I am very pleased with the increased performance without any of the droning or harshness associated with freeflow mufflers.A few people here at work thought the muffler was too large but I think it's the perfect size: It is just as wide and long as my stock TRD Sport Toyota muffler, however, it is half as high so I've gained much needed ground clearance.If you have any questions regarding installation or my 580:1 Crawl Ratio Tacoma, then please post up and I'll do my best to respond.Thank you Magnaflow!!