Best exhaust and engine upgrades for a 964?

[p7guru]

I have searched, but I can't seem to find a straightforward answer.

1. Is there a tolerable exhaust upgrade for a 964 that improves actual hp? How much should I expect?

2. Are any other improvements to the engine even worth it? It lOols like the chips are a wash, and the other stuff looks like snake oil (other than cams and bigger Pistons.

Any worthwhile power upgrades for a low mile street driven 964?

[Joe Bob]

Equal length Heat Exchangers are an improvement. I used 993 HEs, flipped the flanges so that fit. Free flow muffler.....lots of threads on the subject with 3.6 users with SCs and Carreras.

Lose the cat if allowed in your area and I use a No Bad Days sport chip available from Ingo, 3.6@cox.net. His chip has a dual program that allows for sport mapping but keeps the stock program if you are in a smog area.

[jpachard]

The Cup exhaust is a good option and nice since you can have several options. I went with a full cup setup which includes primary and secondary muffler bypass but I install my primary muffler when running at LimeRock park due to noise regs at that track.

I had Steve Wong make me a chip for the above exhaust mentioned. I haven't dyno'ed the car yet but judging from laptimes its very healthy now. Ing's chip is a good option if you live in an area where you need to meet smog.

[Shamus911]

The most restrictive part of the exhaust system on these cars seems to be the headers so swapping them out to a 993 setup or purchasing a header exhaust system yields the most I think.

If you really want to wake the car up, couple the upgraded exhaust with an RS lightweight flywheel and clutch/pressureplate setup and a Steve Wong chip that is mapped for those upgrades.

My car w/a B&B header exhaust and RS LWFW/clutch and Wong chip is literally transformed from where it was stock. BIG difference.

After that - time for better gears (which also makes a big difference in drive ability)

[Bill Verburg]

It's going to depend on how much $ you want to spend

here are the flow rates for the individual sections of 964 exhaust

Section Flow Rate (CFM)
Catalytic Converter 442
Primary Muffler 396
Secondary Muffler 462


the headers though having a poor geometry actually flow fairly well and w/o lumpier cams you don't get a huge advantage from equal length headers any way as long as the pipes are sized right, which 964 stock are




so the most cost effective mod is to replace the primary muffler and then the cat followed by the secondary muffler

That said for a more expensive upgrade go to 993 headers or for even more $ B&B headers or Fabspeed headers.

I've used B&B on several 964 & 993 engines and they are ok, nothing special though. I have been in several w/ Fabspeed headers and mufflers and the also performed well w/ a nice mellow exhaust tone.

here's the Fabspeed setup, they use a larger muffler than most, this really cuts down on the noise level but still sounds great.

[p7guru]

Thank you Bill. That information is very helpful.

[rbogh901]

the flow rates are interesting. I haven't seen those before.

also note that there is data out there regarding dyno pulls with various configurations. rennlist has more if you want too. I can't speak personally but it seems like people report better hp with primary cup pipe but better low end with secondary bypass. and eliminating both doesn't really help, just makes it loud. so the moral is that some backpressure can be good.

what do l know? there's a lot more info out there for sure. most people start with the cup pipe as Bill suggests for the following reasons: improved flow, acceptable noise, reduced weight at the rearmost location, and financially reasonable.

let us know what you find.

[Cobalt]

I went with a 100 cell dansk cat picked up for a few hundred on ebay and a magnaflow muffler which weighs about 6 pounds 3" in out. Had my shop weld the flanges and install for around $600 complete. So under $1000 total investment

This is what the dyno sheet looked like afterwards. Hard to read but it was nearly 95 degrees when this was done. Base line was at 209rwhp on a much cooler day so roughly 38 rwhp increase for very little money. You can get a little more out of these engines with chips and more money, but cost is considerable for the little additional HP gained.

BTW most everyone who hears my car says it is one of the best sounding 911's they have ever heard. Slightly loud but no drone inside like some of these systems will create.

[celal]

I think the best exhaust kit is m&m exhaust its like a formula 1 exhaust well engineering but its very expensive

[Jim Richards]

Originally Posted by Bill Verburg

so the most cost effective mod is to replace the primary muffler and then the cat followed by the secondary muffler

For the person looking for a one step at a time upgrade approach, what primary muffler would you recommend? Thanks.

[ralendrum]

I bought a 1990 C4 a couple of years ago. I don't drive it much because we also have a 996. The 964 came with a B&B header / muffler set up on it. The headers have the heat exchangers but the muffler is set up as 2 in 2 out. The bottom line is that it is too loud to drive for anything but short distances. I had to drive in a lower gear to keep the revs up enough not to drone.

I bought an exhaust sytem off E-Bay. It included the exhaust manifolds, Cat and all the guards. From Pelican I bought the Fabspeed. I love the sound now, I am legal and my wife will actually ride in the car.

[Bill Verburg]

Originally Posted by ralendrum

I bought a 1990 C4 a couple of years ago. I don't drive it much because we also have a 996. The 964 came with a B&B header / muffler set up on it. The headers have the heat exchangers but the muffler is set up as 2 in 2 out. The bottom line is that it is too loud to drive for anything but short distances. I had to drive in a lower gear to keep the revs up enough not to drone.

I bought an exhaust sytem off E-Bay. It included the exhaust manifolds, Cat and all the guards. From Pelican I bought the Fabspeed. I love the sound now, I am legal and my wife will actually ride in the car.

B&B mufflers were notorious for 2 things in back in the day,
1) noise
2) cracking

the noise was improved over time but at the expense of other issues, I wouldn't recommend them

Their headers on the other hand are fine, just hook them up to a Dynomax muffler and you are good to go.

[craig001]

I am surprised that there has been no mention of using a primary bypass pipe instead of a new muffler. Maybe the wisdom has changed since I owned a 964...

[jpachard]

Originally Posted by craig001

I am surprised that there has been no mention of using a primary bypass pipe instead of a new muffler. Maybe the wisdom has changed since I owned a 964...

Craig, see post #3. This is what I use and it works great.

Cheers, James

[rbogh901]

Originally Posted by Bill Verburg

It's going to depend on how much $ you want to spend

here are the flow rates for the individual sections of 964 exhaust

Section Flow Rate (CFM)
Catalytic Converter 442
Primary Muffler 396
Secondary Muffler 462


the headers though having a poor geometry actually flow fairly well and w/o lumpier cams you don't get a huge advantage from equal length headers any way as long as the pipes are sized right, which 964 stock are




so the most cost effective mod is to replace the primary muffler and then the cat followed by the secondary muffler

That said for a more expensive upgrade go to 993 headers or for even more $ B&B headers or Fabspeed headers.

Very helpful Bill.

The flow rates are interesting and I have been happy with my primary bypass to eliminate that bottle neck. The sound is good too.

Here is another question: What are the flow rates for a sport cat and cat bypass?

[GBX]

Originally Posted by rbogh901

Very helpful Bill.

The flow rates are interesting and I have been happy with my primary bypass to eliminate that bottle neck. The sound is good too.

Here is another question: What are the flow rates for a sport cat and cat bypass?

bring back this thread b/c i'd really like to know the flow rates of the above as well. Anyone know?

[Spenny_b]

Speaking to the people (very well respected..) I've spoken to, I wouldn't be spending my hard-earned $$ with Fabspeed; I'll leave it at that, for fear of a flame-war....If it were me, I'd give Pelican'er RarlyL8 (Brian) a call - makes some VERY nice systems and lots of very + feedback from members of this forum.

Chris Carroll @ TurboKraft also know a thing or two about what works and what doesn't with headers and systems, seen most and tested loads.

As I'm over in the UK, and if I had a very healthy budget, I'd go back to Joe @ BTB Exahusts...used to run one of his manifolds on a previous race car, his/their workmanship is beyond fantastic (in this case, the engine was extremely sensitive to primary lengths, and at the time, he was one of VERY few people that could actually make a system to length tolerances of, iirc, 2mm....most just said they could)

[mikedsilva]

Originally Posted by Bill Verburg

It's going to depend on how much $ you want to spend

here are the flow rates for the individual sections of 964 exhaust

Section Flow Rate (CFM)
Catalytic Converter 442
Primary Muffler 396
Secondary Muffler 462


the headers though having a poor geometry actually flow fairly well and w/o lumpier cams you don't get a huge advantage from equal length headers any way as long as the pipes are sized right, which 964 stock are.

Re-post of this older thread, but it has good data from Bill.

Using my stock cat, I replaced my secondary muffler with a g-pipe and ended with a louder note with more "throbbing".. a bit like a noisy WRX. Plus it felt like the car had more torque down low (could be imagining it).

I then put the secondary muffler back on, and replaced the Primary muffler with a straight through pipe.. the result was a more mellow and smoother note and the car didn't "feel" quite as torquey.

Am i imagining it?

I'd have thought if the primary muffler was the main restriction, then by removing it, the result should be better than replacing the secondary?