I recently put a flowmaster 50 series delta (in stainless steel) on my 2004 Tacoma (Xtra-cab, 3.4, auto, 4wd, TRD, ...). It sounds really good, it has a nice deep/throaty sound that does not get "whiny" at higher RPM's (the flowmaster 40 series gets alot of complaints about this). It is loud enough to get people's attention, yet the interior resonance is not annoying. I can really notice a difference in the way my trans shifts- it's much smoother and I do notice an increase in power (I also have a K&N filter installed- I highly recommend it). I decided to keep my truck looking pretty much stock and I only changed out the muffler- I kept the same single output (I thought about getting a dual output, but it would require a lot of work b/c there is not a whole lot of room to run a second pipe out). I highly recommend getting a flowmaster- I should have done this a few months ago when I bought the truck. My other Tacoma had a 3" lift w/ 33" tires- I beat the hell out of the truck and it never gave me any problems even at 180,000 miles. I got broadsided and the truck was totalled. -I plan to lift this truck when the warranty expires (I have a 75,000 mile or 6 year warranty).