[ECUPirate328]

Anybody installed an AFE Catted DP on a N20? There's a lot of info out there on the other DPs but I couldn't find much on the AFE version.

[CandyRedRC46]

I installed an early cattless AFE DP. The fitment was off at the DP to catback joint. So I cut the 2.25" joint off both sides and installed a 3" V-band and flex pipe in their place. Now perfect fit and should flow better too.

[mike@x-ph.com]

Skip AFE and get Wagner , VRSF, AR or Evolution Racewerks

[rjd_F30]

Originally Posted by mike@x-ph.com

Skip AFE and get Wagner , VRSF, AR or Evolution Racewerks

Why skip AFE? And from pictures AR looks like a bad choice, not sure why they would chose to taper it down like that...

[mike@x-ph.com]

Originally Posted by rjdnyy224

Why skip AFE? And from pictures AR looks like a bad choice, not sure why they would chose to taper it down like that...

We had fitment issues with AFE downpipes

AR Design downpipes are showing same gains as any of the proven brands

[rjd_F30]

Originally Posted by mike@x-ph.com

We had fitment issues with AFE downpipes

AR Design downpipes are showing same gains as any of the proven brands

And not with any of those other brands you listed?

I'd figure the gains would be the same, but I still would prefer something that doesn't taper like that, even that preference is unsubstantiated.

[mike@x-ph.com]

Originally Posted by rjdnyy224

And not with any of those other brands you listed?

I'd figure the gains would be the same, but I still would prefer something that doesn't taper like that, even that preference is unsubstantiated.

When you compare the numbers we sold of each brand, the rate of all the other brands are within the acceptable margin

[CandyRedRC46]

Originally Posted by rjdnyy224

Why skip AFE? And from pictures AR looks like a bad choice, not sure why they would chose to taper it down like that...

I will preface this by agreeing with Mike... My AFE down pipe fitment sucked in original form (more on that in a bit).

All down pipes taper down to 2.25" inner diameter. It doesn't matter if its a $99 ching chong ebay special or a $1000 AR/ER/Wagner etc. It doesn't matter if the company that sold it to you advertised it as a 4" downpipe. They all neck down to a 2.25" in dia exit, in order to slip into the factory catback exhaust. The same goes for all cat back exhausts and front pipes. They will all neck down to about a 2.45" inner diameter at the entrance, in order to slip over the factory down pipe....

For some reason none of you people (BMW owners, Vendors or Tuners) seem to care lol. I have had countless people tell me that a couple inch long section of 2.25" piping isn't a big deal and it won't effect performance, but I am an engineer and studied Fluid dynamics way too much for that not to bother me...

So I installed an AFE catless down pipe and a Supersprint 3" front pipe, cut the 2.25" section out and welded in a 3" flex pipe and 3" V-band. Now it flows and fits better than any of the most expensive name brands could ever dream of.

[puts on flame suit. drops mic. end rant. im out]

[rjd_F30]

Originally Posted by CandyRedRC46

I will preface this by agreeing with Mike... My AFE down pipe fitment sucked in original form (more on that in a bit).

All down pipes taper down to 2.25" inner diameter. It doesn't matter if its a $99 ching chong ebay special or a $1000 AR/ER/Wagner etc. It doesn't matter if the company that sold it to you advertised it as a 4" downpipe. They all neck down to a 2.25" in dia exit, in order to slip into the factory catback exhaust. The same goes for all cat back exhausts and front pipes. They will all neck down to about a 2.45" inner diameter at the entrance, in order to slip over the factory down pipe....

For some reason none of you people (BMW owners, Vendors or Tuners) seem to care lol. I have had countless people tell me that a couple inch long section of 2.25" piping isn't a big deal and it won't effect performance, but I am an engineer and studied Fluid dynamics way too much for that not to bother me...

So I installed an AFE catless down pipe and a Supersprint 3" front pipe, cut the 2.25" section out and welded in a 3" flex pipe and 3" V-band. Now it flows and fits better than any of the most expensive name brands could ever dream of.

[puts on flame suit. drops mic. end rant. im out]

Ha I hear you. So of all people I'd think you would agree with me lol. The AR DP not only tapers at exit like you said, but also right before the flex joint, and it looks pretty severe. None of that, including the exit taper to 2.25" will affect performance, but just like I said and like I think you're insinuating, it's can't hurt to have it NOT taper as opposed to having it taper. As mentioned, the preference is unsubstantiated performance wise, but it's a preference I think we both have regardless.

[CandyRedRC46]

Originally Posted by rjdnyy224

Ha I hear you. So of all people I'd think you would agree with me lol. The AR DP not only tapers at exit like you said, but also right before the flex joint, and it looks pretty severe. None of that, including the exit taper to 2.25" will affect performance, but just like I said and like I think you're insinuating, it's can't hurt to have it NOT taper as opposed to having it taper. As mentioned, the preference is unsubstantiated performance wise, but it's a preference I think we both have regardless.

That is a pretty bold claim, but lucky you, I have nothing to back my claim either lol. I do like that the AR Design is a very smooth and long taper to 2.25", as opposed to the abrupt steps of other DPs, but that 2.25" section just went from a small easily corrected section, to a foot long section that cannot be cost effectively corrected. It is a beautiful design though, just not my cup of tea.

[rjd_F30]

Originally Posted by CandyRedRC46

That is a pretty bold claim, but lucky you, I have nothing to back my claim either lol. I do like that the AR Design is a very smooth and long taper to 2.25", as opposed to the abrupt steps of other DPs, but that 2.25" section just went from a small easily corrected section, to a foot long section that cannot be cost effectively corrected. It is a beautiful design though, just not my cup of tea.

It is bold, and similarly I have no evidence either lol. Nothing more than a preference.

[CandyRedRC46]

I really wish I had the time/money/energy to do back to back dyno runs for no other purpose than to settle friendly debates on the internet, but my opinion is there is no way that a true full 3" exhaust on a car making +250whp will not out perform the same exhaust on the same car with a 2.25" section placed in somewhere.

Now whether this is the difference of 5 or 25 whp, I don't know, but on a car that we are all shooting for 300whp in, 2.25" is not adequate.

[CandyRedRC46]

Here is the bottleneck.

[CandyRedRC46]

So cut that section out and weld a 3" vband and flex pipe on instead.

[rjd_F30]

Not gonna lie, those pictures are pretty convincing lol. Definitely a bottleneck physically. But I would imagine that the fact it's a relatively low output, small engine not generating that much exhaust gas volume would minimize any gains from eliminating that bottleneck. If we were talking about a 6.0L 500hp V8 with that bottleneck, yah, that's definitely robbing power. Regardless, impossible to know if it makes a difference without dyno data like you said. I would be very interested to find out.

[rjd_F30]

Also, that pic of the AR DP makes it look way better than the picture I saw. It's a very smooth taper, not as abrupt as I thought.

[Fronttwelv]

Originally Posted by CandyRedRC46

I will preface this by agreeing with Mike... My AFE down pipe fitment sucked in original form (more on that in a bit).

All down pipes taper down to 2.25" inner diameter. It doesn't matter if its a $99 ching chong ebay special or a $1000 AR/ER/Wagner etc. It doesn't matter if the company that sold it to you advertised it as a 4" downpipe. They all neck down to a 2.25" in dia exit, in order to slip into the factory catback exhaust. The same goes for all cat back exhausts and front pipes. They will all neck down to about a 2.45" inner diameter at the entrance, in order to slip over the factory down pipe....

For some reason none of you people (BMW owners, Vendors or Tuners) seem to care lol. I have had countless people tell me that a couple inch long section of 2.25" piping isn't a big deal and it won't effect performance, but I am an engineer and studied Fluid dynamics way too much for that not to bother me...

So I installed an AFE catless down pipe and a Supersprint 3" front pipe, cut the 2.25" section out and welded in a 3" flex pipe and 3" V-band. Now it flows and fits better than any of the most expensive name brands could ever dream of.

[puts on flame suit. drops mic. end rant. im out]

AHHHHHHMEN CandyRedRC46 This is totally unacceptable in the two other communities I have been a part of in the past. If you tell the VW gti/golf r/2.0t community that the new "xxx" downpipe/turboback solution will be $2500, and there's a section of 2.25" piping in there, you will be laughed off the forum. There will be NO sales of that product, I guarantee that. Same with the WRX/STI crowd.

Manufacturers please listen to us and make a solution.

[sspade]

Speaking of fitment... best stay away from VRSF.

AFE is a proven brand (unlike VRSF)... you should not have any issues with their pipe.

[CandyRedRC46]

Originally Posted by sspade

Speaking of fitment... best stay away from VRSF.

AFE is a proven brand (unlike VRSF)... you should not have any issues with their pipe.

I definitely had issues with my AFE down pipe (though it was a very early model that may have been improved by now).

I tried several times to fit it. Once even by a friend at my BMW dealership that is a BMW tech. It simply would not seal tightly at the downpipe to catback connection, so cutting out that connection and welding in a VBand and flex pipe in it's place was a must, just a nice bonus that I went 3" instead of 2.25" like the original connection. I also had to slightly realign the bracket that bolts to the engine block (no big deal).

In my opinion if you buy a down pipe that does not include a flex pipe section, it is going to be very hard to get a perfect, leak free fit. It is also going to add unnecessary stress to the turbo manifold, turbo, down pipe, exhaust system and all fasteners/hardware in between. Why AFE skipped out on this is beyond me, they ought to know better.