I'm planning on modding my 06 6MT soon. So far the only things I've done is rear muffler deletes and high-performance summer tires. I'm planning on installing BC BR Coilovers & dropping around 1.5", getting a Progress rear anti-roll bar, 18x8.75et35 XXR 527 Chromium Black wheels, 255/35r18 Michelin PSS tires, RV6 V3 PCD & J-Pipe, and doing a custom "catback" (though I'll be catless) with 2.5" stainless mandrel bent piping and two MangaFlow 12640 resonators/straight-through mufflers.... I've been pouring through AZ forums on exhaust setups and the RV6 V3 PCD & J-Pipe in particular, but have had no lucky determining whether or not I think it'll still be quite raspy or not too bad, or too quiet, or "too loud".... I'd like some input & thoughts.
I'm also unsure whether or not the MagnaFlow 12640 will fit under my car if I drop 1.5" or so, but that I can obviously measure, I just keep forgetting ha.
Thanks in advance.

that's because NO ONE CAN.
you're effectively doing an experiment.
you may or may not like the outcome...so then you experiment MORE and shape the sound how you want it.

Haha yeah, I know. I'm just trying to get an idea, get others' thoughts first as well.

Yeah, that's my thought and worry as well haha

Be a pioneer and go for it

That's what I'm thinking as well, and planning on. Unless I hear otherwise, and then I'll adjust, but I'm sticking to my plan. Thanks for the input so far!

a few things...

- hopefully you know that the xxr wheels you want in that fitment will not clear your brembo brakes. you'll have to run spacers to clear your brakes. for me, that would kill the thought of getting the wheels, but that's cuz i hate spacers...your call of course

- there's a great thread below that richie put together on estimating volume of an exhaust and what can eliminate rasp. it's not perfect but gives you a ballpark of you what need to kill rasp. i would suggest starting with ONE 12640 resonator and see how that sounds. i think you'll be ok. but to be honest like others have mentioned, every single exhaust setup is going to be different. i've been through probably 6 exhaust setups (if you include hfpcs, jpipe, catback, and 3rd cat options) and i fine tweaked mine until i got it exactly how i want. for example, i got the xlr8 resonated catback....it was fine...then i got hfpcs and i put in resonator 10436 since i had some rasp...then i put in a high flow 3rd cat and sound changed...then i wanted more sound back and put in a 10426 and took out my 10436. now i feel it's perfect for where i'm at in life (noticeable with normal driving, not too loud, but roars on WOT)

https://acurazine.com/forums/3g-tl-p...g-pcds-849750/

it's an experiment! (current setup is hfpcs, atlp j pipe, high flow 3rd cat, xlr8 quad with 10426 resonator)

I am going through that crisis now. I want it to roar at wot, but subtle sound in normal driving conditions. HFPC RV6 long jpipe XLR8 resonated exhaust. I am going to look into your route.

check out the 10426 resonator if you want it to be a little loud still at WOT, but go with 10436 if you want minimum cabin noise but with a good quality exterior sound still. i had both and i could have lived with either, but i wanted slightly more sound after a few years so i switched to 10426.

the xlr8 resonator is so so tiny it's hilarious. it's basically a swollen through pipe haha, i had rasp when i installed HFPCs so i switched it out for a magnaflow resonator.

let me know if you have any questions and i'll try to help you out

Yeah xlr8 resonator is super small. Yeah I have been searching magnflows on summit website. This maybe too big so I need to measure.

https://www.summitracing.com/parts/mpe-12646/overview/

Only reason I am considering is because I am pretty sure the HFPCs are shot and will probably upgrade to the PCDs

If you are going to make your own custom exhaust, then don't waste your time with 2.5" main tube. It's too small for any J-series engine.
The only reason that aftermarket companies use it is because it conveniently mates up to the stock j-pipe. You should have 3" main tube
and then split into dual 2.25" tube in the rear. Some j-pipes can be special ordered with 3" main tube. If you run with PCDs, then you WILL
have rasp and the exhaust smell WILL be obnoxious. But the intensity of the rasp depends on the rest of the system. The 3" main tube
will lessen the intensity, but whether or not it's objectionable is entirely up to you.

Unless you make your own resonators and mufflers, then you primarily have 2 sources of components: Vibrant and Magnaflow.
If you drive your car in the winter, then you will appreciate the Vibrant stuff as it's all SS304. All the Magnaflow stuff is SS409, which has less chromium/more iron.
Straight thru type mufflers and resonators are the same type of construction, so they have the same effect on the exhaust sound.
The larger and/or longer the muffler/resonator, the more attenuation you will get.