For my custom exhaust system im planning add:
single in/dual out
2.25 pipes
high flow cat

My only question is that what kind of muffler would be best for my 4runner 3vze?
I was planning to use the 40 Series Delta Flow muffler from flowmaster.
Any suggestions on what flowmaster muffler should I get?

 

I was thinking the same thing for my own, just 3" pipes. The 40 series has a really deep throaty sound on the 3slows. I like that, but some people don't so it's kind of a personal choice.

 

As the exhaust travels from the engine through to the tail pipe(s) it cools down. When it cools down, the size of the pipe required to maintain velocity drops, meaning that the farther you get from the engine, a larger pipe is not required and can actually hurt performance since a larger pipe than required induces turbulence and said actually restricts flow.

 

So would the 2.25 be better or worse than a 2.5-3? i.e. What's the optimum?

 

3" pipes are a nono on the 3.0... our motors rely on backpressure in the exhaust... without that they are even more gutless than they are from the factory... id go 2.25"... 2.5" MAX...

and i really like my magnaflow muffler... its got a nice deep tone thats quiet enough when im cruising on the freeway at higher RPMs, but sounds really throaty around 2200RPM...

on a side note, i know that its to each their own, but why do you want dual exhaust?? aesthetics? i mean, i like duals, on a fullsize... i just think they dont really look too good on a smaller truck/runner... but thats my .02...

 

Good to know. I'll probably stay at 2.25 then, maybe just a tad more. I've heard more and more good stuff about the magnaflows, and I don't know how you'd go about routing duals on that truck. IMO it's pretty tight down there already with just the one stock..