Yet Another Exhaust Question

[Super_Dave_D]

I just ordered an M&K exhaust and need some rookie advice. Before you say it, I have searched and read a ton of threads but this doesn’t really help my decisions. Your comments are appreciated

Needs and expectations: 88 3.2. and plan on getting one of Steves chips but not immediately. As I said I just ordered the 1-1 from M&K. I am looking for a good sound and whatever HP gains I can expect from this Mod. I addition to the M&K I was going to get a bypass pipe and replace my O2 sensor all at the same time. Is this a good way to go?

What will a bypass do for me? What are the cons?

Do I need a bypass to fully optimize Steve’s chip (future)?

Is there really a big difference between cat bypasses like the Fabspeed or a cheaper one like here on Ebay?

Ebay Cat Bypass

I know this is a lot of questions and I appreciate your input.

Thanks!!
David

[KFC911]

I've had a GHL 1 in/1 out muffler, Fabspeed euro premuffler and a SW chip for several years now, and am very happy with the net results (i.e. sound and performance). From what I've learned from this site, a 'cat bypass' is not as beneficial as a premuffler (search the archives for more info), so you may want to consider that aspect. All three of the products that I mentioned are first rate, and combined together provide a modest, but worthwhile performance increase. IMO, any single mod by itself will not be particularly earthshattering (except for the muffler's sound which made my stereo obsolete...thusly removed ). FWIW, the Fabspeed premuffler was the last of the three mods, and I really couldn't tell much difference before & after, but I have no regrets and would still go that direction if I had it to do over. Hope this helps....

[dmwallace]

I was also doing some research over the last week or so on this same question. I decided to start by replacing the catalytic converter with a Fabspeed euro pre-muffler and have one on order through our host now. I expect to continue to use the O2 sensor with the Fabspeed, and then as a second step will order the SW chip. I am hoping to continue to use the stock muffler for awhile longer.

Regards,
David

'89 911 3.2 coupe

[Nine9six]

Originally posted by KC911
From what I've learned from this site, a 'cat bypass' is not as beneficial as a premuffler

Hmmm,
And here I was thinking that a cat bypass and premuffler were one in the same. Did I just learn something new, or was I correct in my understanding?
If a cat bypass is different from a premuffler, can someone please explain the differences?
Thanks!

[mb911]

david,

There is not allot of differences on the bypasses out there except for finish on them for example polish,raw,painted black. However the euro pre mufflers are said to be the best for performance increases vs the bypass.

So to list cons to the bypass

Cost(maybe a waste in money if nothing is gained)

Hp (may be a loss)


So I would vote no and go with a pre muffler. That said will you notice a huge difference NO probably just bragging rights from dyno sheets..

The biggest improvements will be the chip and the muffler. Then decide if you want to spend the extra money if need be later. Sound will change accordingly as you might assume

[JeremyD]

Do a premuffler and a nice sport muffler like the MK along with a Steve Wong Chip.

Next step up would be SSI's / B & B or GHL - again with a chip.

[Nine9six]

Originally posted by Nine9six
Hmmm,
And here I was thinking that a cat bypass and premuffler were one in the same. Did I just learn something new, or was I correct in my understanding?
If a cat bypass is different from a premuffler, can someone please explain the differences?
Thanks!

Anyone care to chime in on these questions?

[JeremyD]

My understanding when I was researching this is the cat bypass is just a pipe - no stuffing. The premuffler has a stuffing, although slight - the marginal packpressure is apparently good for the 3.2 and with the premuff and sport muffler you can get very similiar results to a more expensive header system.

[KFC911]

Originally posted by JeremyD
Do a premuffler and a nice sport muffler like the MK along with a Steve Wong Chip.

Next step up would be SSI's / B & B or GHL - again with a chip.

The MKs weren't available when I opted for a GHL. If I were doing this today, I would probably go this route that Jeremy suggested. Question: I was under the impression that SSIs weren't necessarily an 'upgrade' for the 3.2s (but are optimal up to the 3.0s)...have I been mistaken? David...just FYI, the first thing I did on my car was install a GHL sport muffler, and the exhaust note alone causes a perpetual grin when driving...it sounds like a sports car now ! Have you considered 'gutting' the stock muffler in the interim?

[JeremyD]

minimal upgrade with the SSI and definitely not worth the bang for the buck. You can get almost the same results with a premuffler and sport muffler/chip.

Steve W can tweek a chip to work with SSI's (or whatever) and get an incremental increase.

[mb911]

I can tell you this about 3.2 and ssis. Steve personally has them on his car that should say allot

[Super_Dave_D]

Originally posted by KC911
David... Have you considered 'gutting' the stock muffler in the interim?

No I never considered that - the M&K is on the way!!! Cant wait!

[KFC911]

Oops...I didn't realize how many Davids were on this thread. My question was directed to dmwallace who is planning on keeping his stock muffler for a while...

[mb911]

Not a bad idea to gut a stock one but here is why not to for me at least

1 what is your goal? Sound/hp?

2 weight?

3 rusty?

4 how much is your time worth?

5 how do you know it really will improve flow and sound?


It should be sadi that I started making these all for the same reasons you guys are looking at. I wanted a cheaper alternative to spending 1000 bucks on a muffler. I also wanted more quality for my money spent. I was not so concerned about Hp but was nice to get an increase if in there. So I went back and looked at the avaition industry and looked at how they built mufflers and then cut a few 911 mufflers apart and started to experiment. I found that You could make a cheaper cost higher qaulity muffler and give you a sweet sweet sound. The major draw back for us these days is the cost of materials is through the roof. Materials alone now exceed half the cost of the product not including time to build them and support them/computers/phones/elctricity/maintence to equipment/ etc.

I know you get the idea I am babbeling. My thoughts I think are explained.

That said I am the worst offender of what I just stated in my list of 5.

I have spent hours and hour adding steel turbo fenders to my car and repainting it with only satisfaction as the reward. along with my custom airboxes and and turbo charger kit I made.

So to close my short story here Go for it if nothing else it is learning thing. It is how I started. I always encourage people to learn what they can about the cars and designs etc. Thats the fun of the cars.

[dmwallace]

KC911,

I was confused myself re. the number of Davids in this posting!

To answer your question - I said I wanted to keep the stock muffler for awhile for 2 reasons. First is money - I need to keep cost for new P-car stuff under the "spouse radar" whenever possible. Second, I really don't have a need for a louder exhaust. My car is missing the engine sound pad already, and I am finding that loud noises are bothering my ears more as the years go by (too many clubs and concerts in younger days?).

With those things stated, if folks have suggestions on better than stock mufflers that don't increase the noise level it would be appreciated.

On a related note, I am seeing some paint peeling from the valence that covers the muffler (also from the inside of the engine compartment) which I assume is due to heat generation from the muffler. Is this a common issue? If so, does repainting the valence take care of this for a few years or is this an indication of some other exhaust related problem?

Thanks,
David.

1989 3.2 Carrera Coupe

[Bill Verburg]

I haven't looked into 964 catpass vs premuffler, but back in the '70s the ROW premuffler was consistantly shown to have more hp/torque on a dyno than the cat bypass of the day.

The reson was the internal shape of the ROW premuffler that guided the expansion of the exhaust gases into and through the unit.

Exhaust flow does not like big steps and sharp edges as it transits the pipes.

[nigel911]

Super Dave,

Did you use to work in Sarasota?

[JeremyD]

I think before I did SSI's or B & B's I would do the flipped flange 993 HE and a M & K muffler. Pretty sure Tyson has this set up on his 3.2 and from what I hear it is making some very heatlthy HP, especially with the 3 position chip that Steve W burned for him. (91 octane, 93 octane, and race gas)

[dmwallace]

Jeremy,

I'm not familiar with the flipped flange 993 HE - what is that?

[JeremyD]

Link to "Flipped Flange" Exhaust