Breaking down the OEM exhaust system

[GT Driver]

I have acquired a secondhand oem system from a mate as he sold his HR. I have seen some videos of people chopping off the mid-pipe or removing insulation from the OEM backbox and was curious about it..

 

Mid-pipe resonator

A bit of a random question - but regarding the mid-pipe resonator on the OEM system, what exactly is inside the resonator 'box'? I know it eliminates rasp, but was curious how rasp is reduced with this. I like the sound it creates when removed, but I think it may be too raspy on WOT for my liking.

 

Backbox

A chap in the USA opened up his backbox and took out the fibreglass insulation and welded it back up - mainly to create more sound. He also took a few sections from inside to make it more free-er flowing. Would such a mod make a huge difference with regards to volume? It's hard to judge from his youtube video, and the fact he has ART decat pipes fitted also. But I think it sounds class.

 

 

 

I love the OEM sound so I'm not looking to replace it for a new exhaust, which I can guess most people would just suggest I do !- I am mainly just curious what ways the OEM exhaust volume can be increased whilst not introducing/creating more rasp at the same time.

[HEADPHONES]

I must admit that guys modified OEM exhaust sounds really nice

[Dave6188]

Sounds mint, I have considered doing this myself, if anyone has an OEM backbox for cheap near Hull Pm me and I will have it off you so I can do this mod please. Just hope it doesn't drone !

[GT Driver]

I reckon I'm going to get the backbox mod done in the next week or two. I have a guy that is doing my mates e92 M3 backbox so if that works out ok I'll mine done.

 

I'm going to mimic what the guy in the YouTube video has done - fibreglass out and some baffle removal for free-er flowing. I'll post up videos once done.

 

I'm going to leave the resonator in place. I don't want rasp.

[Dave6188]

Let us know how you get on, most importantly find out if it drones at motorway speeds, if it does I won't bother but if not I'm definitely doing this 😉

 

Sent from my SM-G901F using Tapatalk

 

 

[Dr.Factory]

I can tell you that when I had 100 % stock exhaust I first tried to remove the mid pipe resonator and it sounded like sh*t I then bought a new full exhaust and it was a lot better.... never tried to gut the stock silencer in this car but I have tried that on my old bmw z4 3.0i , and that sounded like sh*t too

[GT Driver]

So a quick update on this - I've had the spare OEM backbox opened up and the fiberglass sound insulation has been completely removed. It was quite an easy job - the fiberglass is located in the third internal 'chamber' on the right. This was then welded shut and fitted on the car. Unlike the guy in the video in my first post, I did not cut out any of the internal chamber walls to increase flow.

 

Now I can understand a lot of people would ask why I didn't just get a cobra or other aftermarket exhaust but I completely wanted to keep the stock tone of the exhaust and the results are pretty good:

 

Exhaust volume increase of an estimated 15 to 20%. Not that dramatic but it's just about right without being too obnoxious or intrusive.

The exhaust tone is pretty much identical to stock - its just louder. There is zero drone and zero rasp.

Cold start is far louder.

When hot: exhaust pops and crackles on the overrun are much more noticeable and not as muffled!

 

For those interested in performance - there is no noticeable loss (or increase in torque). The exhaust seems to rev more freely with the packing removed, very slightly though.

 

 

Edit - here is a vertical video taken just after fitting (fully warmed up). Best listened to with headphones.

 

https://youtu.be/3H-IhaKXaRo

Edited May 29, 2017 by GT Driver