garrett376

I am curious if anyone has already seen the internals of a stock primary muffler (not the catalytic converter) on the 964, or even better, if there is any kind of drawing or pictures out there?

I am planning on opening up my primary to create a sport muffler (as done on early 911's) and just wanted to have a head's up if the information is out there! It could save me from cutting a huge panel in the muffler body! Thanks!

Andy Roe

Have a look on www.design911.co.uk under the 964 exhaust section. They have a couple of videos that you can download explaining different exhaust upgrades and they cut open both the primary & secondary mufflers.

Andy

garrett376

Andy, thank you! I'll go take a look!!! I appreciate the tip!

JasonAndreas

HERE are some great cut-aways photos of various aftermarket and stock mufflers.

garrett376

Thanks Jason, perfect!!

garrett376

It's interesting that in those pictures, it appears that the internals are solid pipes whereas I just cut mine open and they are all perforated! I wonder if my muffler is different from the one in the picture (or the picture is not good enough...). I can't see how, with everything being perforated, this is a "more restrictive muffler" as described in that video.

One fact - it's heavy as heck! It's double layer steel with a ceramic inner layer sandwiched between - no wonder it weighs so much! And it's a thick one to cut through!!

PC2

That's very interesting ... Pics please!

garrett376

Here we are so far...

garrett376

It's a nicely constructed muffler... I don't think there's room to improve anything except the weight... so I am researching a custom setup where I use a lighter muffler (your basic $50 "turbo muffler") in its place.

Gus

Just replace it with a bypass pipe (pipe only) you will save on the weight and the sound is a lot better -
The by-pass pipes come up on ebay every now and then and are jsut an easy pop in-
Save yourself some trouble - you'll liike the sound -

garrett376

It'll be too loud totally open... I already have a cat bypass, and a secondary bypass with zero sound insulation throughout the entire car with semi-solid engine mounts - I'd be deaf and/or toothless by the time I reached the track

Gus

Didn't know that you had already dropped out the secondary - If you have done then I would look at just getting a glass pack with the 3" inlet and outlet that will fit in place of the primary - They are in the market as some one has made that mod - I kept my secondary and replaced the primary with a by-pass - also cat bp - sound is geat - not to loud and quality of tone is good.

garrett376

Hi Gus - I actually did that - bought a $30 fiberglass filled "turbo muffler" and rigged it all up, and it didn't work so well. By the time I was done bending, welding, fabricating a mount, it weighed about the same as my perfect fitting "modified" primary muffler. The car sounds incredible with the opened primary - when idling it sounds fabulous! Now if I could jut get it off the jackstands so I could drive it!

Gus

I think the article I read on the fiberglass-pac install job - he used a second hand primmary for parts - cut off the ends and used some 3 inch pipe to weld it up. Used the original primary as a template so to speak - just less muffler area, more pipe -
Have you look at putting a 993 header system on ???? -

pete000

Have you looked at the Fabspeed web site for the video's on the 964 mufflers? They claim the primary is not an efficient design and the secondary is an actual better design. I am concidering one of their mufflers. I like having the secondary off the car, but feel the stock primary is a bit too loud and aparently a bad design.

If you modify the stock primary internals wouldn't it be really loud?