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      03-06-2019, 08:12 AM   #8
CandyRedRC46's Avatar

Drives: 2013 328i
Join Date: Feb 2018
Location: Florida

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Originally Posted by rjdnyy224 View Post
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]

Last edited by CandyRedRC46; 03-06-2019 at 08:18 AM..