Ok, before you grab your pitchforks and yell at me saying "get the magnaflow 12578/12579" just hear me out. This is where I'm currently at: ebay cast manifold, Garrett 2560R, 2.5" downpipe and midpipe, and the RoadsterSport3 muffler. I ended up only making around 260 whp with the 2560R maxed out (18-20psi) which makes me think that the 2.5" RS3 muffler is a little restrictive for my needs (I'd like to see 280 until I can fork out the cash for a Gen 2 GTX2860R or something in that territory). I also want something a little bit louder (I'm young and stupid, yes), but not straight pipe loud.

I took off the muffler last night to do some virtual dyno pulls to see if I picked up any power, but then found out my laptop was dead. Anyways, the straight piped exhaust is stupid loud and sounds like a shitty tractor. I was considering transitioning from 2.5" to 3" at the axle and mating it to this Ace Race 3" resonator or perhaps this Vibrant Street Power muffler. Any inputs or recommendations? My understanding is that the miataturbo.net magnaflow mufflers will be too quiet for my taste. Currently, I street drive the car with the exceptions of a monthly autocross and/or drag racing. Even without a muffler there are cars that are much louder at both events, so sound limits aren't a huge concern. I just don't want to wake everyone up that lives in the houses that I drive by on my way to work in the morning.

And sorry for making the 10 billionth muffler thread. Most that I've read are asking about how loud a straight pipe is or how to make it as quiet as possible. I've done a ton of searching too, trust me. I'd like something in between the RS3 (which isn't exactly "quiet" as it is) and the straight pipe.

 

Unfortunately you're not going to gain 20whp from switching to a 3" axle back. I would do your virtual dyno test first.

 

My crappy tuning laptop kept refusing to hold a charge, but I briefly got it to work today. Very disappointed with the results, and you are correct. No noticeable difference between having the muffler and no muffler. Onto different paths to try to bump up the numbers with this turbo. One good way to improve exhaust flow would be "porting" my 2560R to match the flange on my eBay manifold. The flange hole on the manifold is T3-sized (if I am not mistaken) and the abrupt transition to T2 is probably leaving a lot to be desired. Looking at the datalogs I'm only hitting 10psi at 3700rpms and it takes until 5000rpms to hit 20psi in 4th gear from 2000rpms... very undesirable. Making me want to pull the trigger on a full Kraken setup...

//close thread :(