Muffler cat bypass question
 

A question or two for those here who are in the know.

My Targa came with a single in/single out B&B muffler on it when I bought it. I really like the sound as do others (I have had several people mention it). Not to loud, but nice.

Well since I have the engine out and am doing a myriad of things, yet another "while I'm in there..." moment occurred. I started kicking around the idea of a Pre-Muffler Cat Bypass from either Fabspeed or M&K. The only thing that concerns me is that I don't want anything that will end up all that loud. There should be some small power gain and in the end I want to couple everything with a SW chip. Going to stick with the stock HE for now.

Could or should it be a good combination? Any downsides? Any info/input appreciated. Thanks in advance.

Our pre-muffler will keep it more quiet while improving power. Steve has chips for that exact setup and has done a ton of them.

vs?

I've got an m&k pre-muffler and 1 in 1 out silencer. Sounds great, quite rumbly low down but throaty and rorty up top. I like it. Quality seems to be there too. Nice workmanship.

Sound is subjective, each to his own and all that but I don't suppose you'll be unhappy no matter which way you go. The b&b silencer is another excellent choice. Not sure how much a pre-muffler will make over what your car sounds like now.

vs a cat bypass pipe.

i swapped my cat for a dansk pre-muffler and like the results. it's a little deeper under 2k rpm, after 2k is sounds like stock. stock muffler too.

I really don't want to sound stupid........But, what exactly is the difference between a pre-muffler and a cat bypass?? Thanks

Cat bypass (sim to a bursch) is simply a straight pipe of equal diameter thru it's whole length.
A pre muffler has a smaller inlet/outlet with a larger diam section in between that has some kind of baffling in place but is still very 'open' for flow. More tuned than a straight pipe.
I've used both and find the pre muffler gives good opne flow but better low end grunt than a straight pipe.
With a stock or other muffler the noise level is less for the pre muf for obvious reasons.

I put a gutted 3.2 muffler - totally empty - on my SC and it sounded great to 5k rpm then sounded only loud beyond that. Very boy-racer and tinny. I had a Fabspeed pre-muffler.

Some back pressure must better than nearly none on a car that is not a fire breather. Sounds good now with the stock SC muffler at high RPM's but it is by no means knarly.

I had an MK pre muffler before i went to full headers and it's a beautiful piece of work and has the O2 bung which captures both banks,something the other brands don't ...

Definitely would recommend the MK !

Cheers !
Phil

Thanks

CAT bypass vs pre muffler
 

If I have a stock muffler and replace the CAT with a pre muffler will I get more of a throaty tone with a slight boost in HP ?
I do not want it to be overly loud just less tinny.
Of course this can be subjective but hopefully not too vague.

M&K Euro pre-muffler, M&K 1-in 2-out GT3 muffler, Steve Wong Chip
IMG_0274.MOV - YouTube

it will sound a little deeper under 2k but normal after that. i doubt you will gain anything noticeable, if at all. if you want to change the sound you need a different muffler.

I agree, as I have that exact setup - M&K pre-muffler with stock banana muffler. The car sounds very little different than stock. Eventually, I'll add a sport muffler of some sort, but that's a ways down the priority list right now.

So,
If am interested in:
A lower more throaty tone without being overly loud (can be louder just not TOO LOUD)
keeping the heat
illuminating the CAT
Getting an HP bump
Keeping the existing single out on the left
and
It doesn't have to be stainless.
Recommendations ?

and less expensive trumps more $$$ of course

I'd do it in steps. First, if you want to eliminate the cat w/o a lot more noise, you will need a pre-muffler, not a cat bypass. I'd do that first.

Second, you'll want a different 1-in/1-out muffler. I'm not qualified to make recommendations on that yet. As a guess using what I've heard on others' cars, I'd say either an M&K or perhaps a Dansk. I know the M&K GT3 style I heard and drove a while back had a great deep note, but was perhaps a bit loud for my neighborhood. I'm hoping that the 1-in/1-out has a similar—but quieter—sound.

You won't loose heat unless you go to headers. The CAT may make things run a little hotter but you won't gain much HP, unless it is shot and restricting flow because it is clogged. This upgrade is mostly a sound upgrade in my opinion. If you reduce back pressure too much you may actually reduce the performance.

What if I just gut the CAT ?
Wouldn't that be like a cheap pre muffler ?
I have done that on other cars.

I really am just flying by the seat of my pants here.
(The advantage is I can just pull over instead of having to land the beast)

Gutting the cat is an option....keep in mind a cat IS part of the operating system and you may have differences in performance, exhaust smell and sound.