I am install this Supersprint 784302 decat pipe before one week. Here is my 5c about this part.
Advantage:
1. Sound is fantastic (I have also rear SS mufler). Now litle louder but car have one additional deeper noise altogether with original sharp and brisk sound one m3 e36. Sound is more powerfull because original cat section dont have this deep portion sound. Sound is now like combination M50B25 engine and S50B30 engine. Excellent.
2. Entire pipe is lighter and smaller.
old section:

http://img217.imageshack.us/img217/586/supersprintdecat784032mwm3.th.jpg (http://img217.imageshack.us/my.php?image=supersprintdecat784032mwm3.jpg)

SS decat inward
http://img511.imageshack.us/img511/306/supersprintdecat784032mci0.th.jpg (http://img511.imageshack.us/my.php?image=supersprintdecat784032mci0.jpg)


http://img517.imageshack.us/img517/3303/supersprintdecat784032muq2.th.jpg (http://img517.imageshack.us/my.php?image=supersprintdecat784032muq2.jpg)
http://img210.imageshack.us/img210/1016/supersprintdecat784032mgu4.th.jpg (http://img210.imageshack.us/my.php?image=supersprintdecat784032mgu4.jpg)
http://img217.imageshack.us/img217/959/supersprintdecat784032mrz4.th.jpg (http://img217.imageshack.us/my.php?image=supersprintdecat784032mrz4.jpg)
http://img210.imageshack.us/img210/1514/supersprintdecat784032mfq1.th.jpg (http://img210.imageshack.us/my.php?image=supersprintdecat784032mfq1.jpg)

mounted on car:
http://img511.imageshack.us/img511/5388/supersprintdecat784032mse3.th.jpg (http://img511.imageshack.us/my.php?image=supersprintdecat784032mse3.jpg)
http://img210.imageshack.us/img210/149/supersprintdecat784032mzr6.th.jpg (http://img210.imageshack.us/my.php?image=supersprintdecat784032mzr6.jpg)
http://img125.imageshack.us/img125/8682/supersprintdecat784032mfa9.th.jpg (http://img125.imageshack.us/my.php?image=supersprintdecat784032mfa9.jpg)
http://img125.imageshack.us/img125/8320/supersprintdecat784032mdo7.th.jpg (http://img125.imageshack.us/my.php?image=supersprintdecat784032mdo7.jpg)
http://img210.imageshack.us/img210/8044/supersprintdecat784032mlu6.th.jpg (http://img210.imageshack.us/my.php?image=supersprintdecat784032mlu6.jpg)
http://img511.imageshack.us/img511/8894/supersprintdecat784032mjq2.th.jpg (http://img511.imageshack.us/my.php?image=supersprintdecat784032mjq2.jpg)



Disadvantage:
CAR LOOSE TORQUE IN LOW/MID RANGE!!! Here is dyno test for evidence:
http://img393.imageshack.us/img393/5288/dynom3e36supersprintnv6.th.jpg (http://img393.imageshack.us/my.php?image=dynom3e36supersprintnv6.jpg)

movieeeeeeee:
http://www.youtube.com/watch?v=8F8KIXImWyk

After this dyno test i am litle confused. In range between 2-3500/min I can feel litle loos of torque, but from 4000/min car pull realy good. Pull like have +20PS in entire range. Maybe this is only one psychoacoustical effect in my brean because car sounds much stronger.

My conclusion:
Original is simply better for perfomance. If I find original section with low miles I will go back to original.
But if you want realy good sound and loosing torque is not drawback for you this is way to go.

Is there multiple versions out there?

I know there was a normal and a race version of the decat system. But the normal ones I have seen didn't have the X section, just straight pipes?

Is there multiple versions out there?

I know there was a normal and a race version of the decat system. But the normal ones I have seen didn't have the X section, just straight pipes?
I dont know. My version have racing label on it:
http://img210.imageshack.us/my.php?image=supersprintdecat784032mgu4.jpg

Interesting.

I have the racing version and I like it overall. I have it plugged to a Scorpion end section exhaust, ist loud and I love it.

I didnt do any tests to see power before and after, but with the turbos working hard my guess is that the de-cat is helping the engine to breath more than the cats would.

Interesting.

I have the racing version and I like it overall. I have it plugged to a Scorpion end section exhaust, ist loud and I love it.

I didnt do any tests to see power before and after, but with the turbos working hard my guess is that the de-cat is helping the engine to breath more than the cats would.
Dyno is only way after which you can know what you have. Marketnig numbers like +50ps with chip, +35ps with exhaust, +20ps with air filter is all bullshit. YOU MUST GO TO DYNO.
When someone asking me about power of my car I dont want to lie. I have prove for my words, dyno print. 99% people don't know anything about power of their cars. I think that any serious driver must have dyno print. This is big help and can realy show how to drive it. One example: why rev car to 6000/min if power drop bellow 5000/min?

Thats true, and thats also why I dont answer when people ask me how much power I am making.

It sounds simple, just take your car to a dyno, but the dynos available here in Luxembourg will not do a test on my car, the nearest one is in Brussels, 2hours away. Im will have to make the trip when i have the time.

BUt I dont buy exhaust mods to get power.. becouse it does not yeld that much. But with the increased boost a more opined exhaust should help.

Two more drawback is that engine run very anxious/turbulent in idle and car convulse with 784302 decat.

Today I am mount back original mid-section section and car is NOW FANTASTIC: smooth idle, no anxious/turbulent, car pull hard from low to high rpm, no any hool in power.

This case is one more example that good car manufacturer like bmw best know what is ideal compromise!!! Especialy on car like ///M3.

chiao

Ok, This could explain my situation also. Maybe I need to look out for a new mid-section.. and get rid of the Supersprint.

Hi Foler -

Thanks for this info. You're right that dyno testing is needed to properly evaluate any new mods to your car. I'm installing an S50B32 into my car and your dyno info convinced me to stick with the stock cat section.

Thanks!

I think that any serious driver must have dyno print. This is big help and can realy show how to drive it. One example: why rev car to 6000/min if power drop bellow 5000/min?

ANSWER: To avoid an awkward shift point on the track.

But we know what you mean.

Thread is very interesting, and, I believe it is the second time in the forum that people have called the SS resonator section to task regarding performance upgrade.

For people in the US market, we're extremely limited in selection of "bolt" on midsection pipes, and its always been "assumed" I believe that the SS midsection is an improvement in terms of weight as well as allowing better performance.

The only un-answered question about the pipe is..... are there situations where it may still be favorable. For example on FI. Or, cammed, custom tuned engines might reveal a restriction in the factory setup that the SS relieves. At least at the airflow characteristcs of a stock motor, as here, it appears that stock out performs SS resonator.

On a side note, for an aftermarket cat-back exhaust do you take the heat shields off the stock pipes and put them on the new pipes or do we really need them?