Replace mufflers only, or worth it to go full system?

B6/7 S4/RS4
#1

I’ve been kicking around changing the exhaust on my '04 Nogaro S4 6 speed. I am debating between just changing the last mufflers or whether it’s worth it to go with the whole cat back system. Has anyone just changed the rear mufflers, leaving the resonators, cats, etc? I would probably go with either Magnaflow, Borla or Flowmaster. I know that justt going this route will not net a great deal of power, but from what I’ve read, even the full systems are only good for 10-12 crank hp.

I’ve searched a lot of different posts, but don’t seem to see this one specifically.

Thoughts?

#2

There is another thread just like this one! 2.75" all the way!:slight_smile:

#3

Good question. On the B67 s4 the exhaust is a big deal. Untuned the exhaust isn’t much of a gain due to the ecu limiting power add the best tune for the s4 (jhm) those numbers jump huge amounts. A good catback and dp with the jhm tune get you almost 50whp and 50wtq.

So if your looking for power your going to need to really look at the exhaust

#4

This is about an S4 :wink: I think

#5

Yeah, 2.75" is a little excessive for the S4. 2.5" is ideal.

#6

Opps i should have read the whole thing! Lol sorry!

#7

Get a catback. Just keep your eye out for a used FI or Stasis (if price is a problem) as they are 2.5 inches and benefit the most. FI is what you should really look for as they are still in business and seem to be the better exhaust.

#8

You’d be best off getting a used FI as suggested. New FI or magnaflow would be a choice also. Magnaflow has a very reasonable priced exhaust. You’ll spend over half the cost of a new exhaust when you add up the cost of just replacing mufflers. Between the price of the mufflers and fabricating them to fit. You’d be better off just getting a proper exhaust.

#9

Exactly. I forgot about Magnaflow. There is a coupon code somewhere on Audizine and you could get one for like 700 shipped i think.

When i did my mufflers it cost me 600 bucks for the mufflers and installation. We needed new piping to make it fit (about 200 bucks) and then labor was another 200. Mufflers were like 240 ish. All in all i spent about 600 just for new mufflers. BUT i wanted to try the setup in hopes i had something unique. Im very happy with the system. BUT for 800 or so bucks you can get a used FI exhaust and for 700 new a magnaflow. Its not cost effective or performance effective to just switch out the mufflers IMO.

#10

The magna catback isn’t the greatest fitting system there is but it’s cheap. What are you doing with your dps. Are you leaving them stock.

#11

It may not be excessive if you have a JHM SC S4. I would love to test that out. Wonder if a RS4 2.75 inch exhaust would fit on a B6/7 S4 with some unique adapters.

#12

http://performancepeddler.com/catalog/magnaflow-16586-performance-exhaust-system-p-31168.html
If you type in audipipes in the ‘coupon code’ area you can get the Magnaflow CB for $714.47 shipped.

If you can find a used FI, by all means go for it, but I have been waiting for one to pop up for the last year and havn’t found one (that someone is willing to ship). I want to ditch my Milltek, but I think I am going to go 2.5in DPs and JHM tune first.

#13

I was actually wondering that myself. I know 2.5 is most optimal BUT if you have the JHM blower would increasing to 2.75 be more beneficial?

#14

I know that when testing a nitrous kit on a B6 S4, 2.25" was worst (Milltek FTL), 2.50" was better (JHM custom 2.5" x pipe), and no exhaust (open headers) was best.

#15

Would love to hear 2.75" plus JHM headers. It sounds nasty enough as it is!

#16

The s4 heads actually flow more then the rs4 heads as the s4 heads have one more intake valve. The 8000 rpm of the rs4 makes the 2.75 almost a must but with the new stage 2 built motors from jhm I think the 2.5 might not cut it anymore for the s4. I did notice a bigger gain removing my 2.5 at the track with the nos testing. I have that post here somewhere with the results.

#17

Interesting. Wish someone with a S4 Stage 1 would put somehow find a 2.75 that fits and test it.

#18

I ended up going for the cat back magnaflow system. I am thinking of pulling the DPs and making piggie pipes out of them. Even if the system isn’t the best fitting, I can make it work. I have a lift to use and the fab tools I need to make it fit nicely.

If I gutted the precats, I’d need to buy one set of spacers (or should I buy two in case I needed them?). Would it be worth my time/effort to make test pipies to replace the cats, or am I going to have a lot of CELs as a result of that?

Seems like everyone goes to JHM for a tune to reduce the CEL problems, but I have the proximity problem - I’m not near them. I do have a good shop who can do a GIAC flash if I needed it, or I can send my ECU away (I have a truck to use if I needed to).

I’d like to make the most of it while I have it apart. But it’s still an S4, so RS4 thoughts and dreams stop here. Ha ha.

#19

First thing don’t waste your money on a giac tune for your s4. It would be a waste of money. Everyone gets the jhm tune because it makes about 30hp and 30tq more then everyother tune and it will help keep the cell away. The jhm tune can be flashed from your house. The have a flash cable you can buy and do it from your house.

Removal of the precats is s big must. That would be top of the list

#20

Do not waste your money on GIAC, even if you have to purchase a cable to flash the JHM tune you can turn around and resell the cable to the next guy without a loss. There are also plenty of guys out there who will let you borrow their cable.

Even if you aren’t a 1/4mile guy (we use it to benchmark real life acceleration on AR, not dynos), take a look at the list. It is dominated by JHM tuned B6/7 S4s, I think one GIAC tuned car is up there and the time is slower than most guys run stock. GIAC is a great company for other platforms, I had their software on my 1.8T like 8 years ago and it was better than most of the competitors, but only one “real” option exists if you have a 4.2l V8 and that is JHM.

Lastly, if your a guy that loves numbers or wants to see gains on paper…I did my own before and after testing on a local dyno and at the strip.

Nearly 40hp/40tq gain with tune/full exahust (most of the other mods made more of a difference in acceleration and wouldn’t show on the dyno)

I was running 13.7x best in the 1/4mile stock, after the mods in the video I went 13.14 and probably coulda/shoulda went high 12s. Those are amazing gains for basically a tune and full exhaust on an NA car. Also, FYI a few weeks later I upgraded to the JHM IM and went 12.86 (best) and that night I had a handful of 12s passes, which not many guys out there can say. This IMHO is all thanks to JHMs hard work and dedication, I just installed the parts and shifted gears.


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Watch “B7 S4 Before and After Dyno” on AudiRevolution.net