Excessive rasp from Bimmerworld X Pipe or is this normal?

[MShift]

After reading a bunch of reviews and watching all the videos I could find I pulled the trigger on a BW x pipe. Sadly I'm extremely disappointed with the low rpm metallic rasp that my car has now. I read that there was a bit of rasp associated with the BW x but I didn't imagine it would be this bad. It sounds metallic, like something is loose, but I've had two shops look at it and same results. Is this normal or is there something else going on here? Rear end is a Dinan which never made this noise before the new x pipe install.

The rasp only happens between 2000 and 2700 rpm, sounds great before and after that. Don't hear it on very light throttle/load or revving it in neutral, but the moment I get on it a little more at that rpm it's pretty bad.

Anyone else experience this or have seen this with the exhaust combination?

[DRLane]

Originally Posted by MShift

After reading a bunch of reviews and watching all the videos I could find I pulled the trigger on a BW x pipe. Sadly I'm extremely disappointed with the low rpm metallic rasp that my car has now. I read that there was a bit of rasp associated with the BW x but I didn't imagine it would be this bad. It sounds metallic, like something is loose, but I've had two shops look at it and same results. Is this normal or is there something else going on here? Rear end is a Dinan which never made this noise before the new x pipe install.

The rasp only happens between 2000 and 2700 rpm, sounds great before and after that. Don't hear it on very light throttle/load or revving it in neutral, but the moment I get on it a little more at that rpm it's pretty bad.

Anyone else experience this or have seen this with the exhaust combination?

What was your prior xpipe? Not sure I hear any rasp.

[b4hand]

Mine does that but I love it and nothing is loose. You should add some resonators to remove the rasp if you don't like it.

[Redd]

Completely normal for catless unresonated x-pipe. That said, your rasp sounds a bit more tinny than my exhaust (non-BW). If you wanna get rid of it just put in some resonators. Or drive above 3k like I do. Lol

[SYT_Shadow]

Did you get the completely unresonated one?

Even the resonated one has relatively small resonators. If you dislike rasp you may need to add a couple.

[MShift]

Originally Posted by SYT_Shadow

Did you get the completely unresonated one?

Even the resonated one has relatively small resonators. If you dislike rasp you may need to add a couple.

No, I got the resonated one. I had a different brand before and it had zero low end rasp.

I want to keep it because it clearly makes power, but that may mean having to change the rear portion.

Adding another set of resonators is a good option too, may be the easiest way to go, but I'm worried it won't really fix the issue.

[SYT_Shadow]

Originally Posted by MShift

No, I got the resonated one. I had a different brand before and it had zero low end rasp.

I want to keep it because it clearly makes power, but that may mean having to change the rear portion.

Maybe just add a couple resonators to the current one?

I hear the resonated one quite often as two friends have it and it sounds fine to me, but different rear sections and different tastes make the final experience different to different people

[MShift]

Originally Posted by SYT_Shadow

Maybe just add a couple resonators to the current one?

I hear the resonated one quite often as two friends have it and it sounds fine to me, but different rear sections and different tastes make the final experience different to different people

Yeah, I wonder if there's anyone on the boards that has that setup. I love the sound otherwise, I don't want to quiet it down at all, I just want to remove the rasp.

What rear sections do they have?

[SYT_Shadow]

Originally Posted by MShift

Yeah, I wonder if there's anyone on the boards that has that setup. I love the sound otherwise, I don't want to quiet it down at all, I just want to remove the rasp.

What rear sections do they have?

One is fully OEM, the other is OEM mod 2 pipes

You could also just add the extra resonators to the primary cat area. This is what ESS sold with their 4 resonator xpipe back in the day

[fth001]

I have the BW resonated X-pipe with a Gintani Race rear and I also have that loud metallic rasp at about 2000-2500 rpm. There's a noticeable difference above 3K but it really feels down on power below that. My car previously had AA test pipes with the secondary cats removed and it didn't feel bogged down below 3K like it does now. I am now switching to a MS X-pipe to see the difference.

[MShift]

Originally Posted by fth001

I have the BW resonated X-pipe with a Gintani Race rear and I also have that loud metallic rasp at about 2000-2500 rpm. There's a noticeable difference above 3K but it really feels down on power below that. My car previously had AA test pipes with the secondary cats removed and it didn't feel bogged down below 3K like it does now. I am now switching to a MS X-pipe to see the difference.

Very interesting that you say that because I felt the same loss of power/response at low rpm, feels like it has more top end though, which is probably why the peak HP is higher with the forward X. We don't really spend a whole lot of time down below 3k rpm when driving quickly though so the trade off may be worth it. I do miss that instant response the car had before...

I'm going to get dynoed later this week to see how much power this setup makes.

Active Autowerke is close to me so I was just going to pick up their resonated xpipe and sell the BW.

If I do go that route, I'll also dyno that setup and report back some numbers/comparison graphs and videos. There could be a chance to also dyno with a different 200 cell, normal x position x pipe, it would be really cool to get dyno numbers on all three and put a few questions to rest.

[tdott]

The power loss / hesitation might be a tuning issue with a more free flowing exhuast.

Here is another thread about it, we got some logs to definitely confirm something is up.

My tuner has also confirmed he makes no changes below 3k. So that could explain things. We need to get a tuner to look into it.

https://www.m3post.com/forums/showthread.php?t=1716181

[MShift]

Originally Posted by tdott

The power loss / hesitation might be a tuning issue with a more free flowing exhuast.

Here is another thread about it, we got some logs to definitely confirm something is up.

My tuner has also confirmed he makes no changes below 3k. So that could explain things. We need to get a tuner to look into it.

https://www.m3post.com/forums/showthread.php?t=1716181

Hmm, never thought of it as a tune issue. I have BPM stage 2 and this was never a problem on the previous catless, resonated x pipe I had. Feels more to me like the design of the X location is efficient at higher rpm as the scavenging effects kick in, but low rpm there's not enough flow to take advantage of that effect and is in fact a little detrimental. I'm not an engineer, but maybe if the rear section is a little more restrictive then that accentuates the low rpm scavenging issue.

I'm really hoping it isn't something else like the car pulling timing due to knock. Only a dyno run log will confirm that. Will hopefully know soon.

[TechE]

It's normal, unfortunately. I thought something loose was rattling at first. I bought new clamps for the rear because they're old and stretched out, so I figured they may help. Now I'm about certain they won't. I'm using the OEM exhaust still, so I'll see if anything changes with my Eisenmann sport when I throw it on.

[darkbmw]

Change your muffler, to a dinan, or active they have chambers which removes the rasp.

[MShift]

Originally Posted by darkbmw

Change your muffler, to a dinan, or active they have chambers which removes the rasp.

I have the Dinan... bad rasp.

I bought dual 12" resonators, should have them installed this week. I will report back with results.

[Gossypiboma]

Originally Posted by MShift

I have the Dinan... bad rasp.

I bought dual 12" resonators, should have them installed this week. I will report back with results.

Yes, very interested in your results.

[tsk94]

I have a the BW resonated X-Pipe with OEM axle back and sounds very similar to this at low RPM - nothing wrong imo.

[Route 16]

Originally Posted by tsk94

I have a the BW resonated X-Pipe with OEM axle back and sounds very similar to this at low RPM - nothing wrong imo.

I have rogue engineering test pipes and straight piped the rest ending with an iPE muffler. I know exactly what you're hearing OP but I don't get that at low RPM's I have to be about 4.5 and up and really on it. I thought it was normal, now I know it is, I like it.

[MikeYQM]

I had that same concern with my BW X-Pipe. Added the same Vibrant 1792 resonators just down from the X and it cleared up most (but not all) of it. I might add HFC or another set of resonators in the spring summer, but I'm not convinced I need it yet.

[MikeYQM]

I also have a power dip at the same point in the power band where the engine feels like it's bogging

[kyrix1st]

These cars are known for "resonance" around 2000 rpm, it is even stated in the factory manual (as normal phenomenon).

I think the "issue" amplifies if you go straight pipe. My setup makes a similar sound around that rpm range.