Z4 resonator delete

Kiashi123

Member
Hi guys, so i have z4 28i and am thinking about deleting resonator for a little louder exhaust with bubbles. Is it worth it? Any negative side effects?
Just want a little louder / stronger exhaust sound to fit my 300hp car 😀
 
I'm looking to do the same and have researched a bit, I was looking at mid box delete like this video:
https://www.youtube.com/watch?v=963Or1nGAcQ

From others that have done it you wont get drone on motorways and it is a little louder, I'm just trying to find a decent custom exhaust garage to do the work and save the £'s for it.
 
Jay-Jay said:
I'm looking to do the same and have researched a bit, I was looking at mid box delete like this video:
https://www.youtube.com/watch?v=963Or1nGAcQ

From others that have done it you wont get drone on motorways and it is a little louder, I'm just trying to find a decent custom exhaust garage to do the work and save the £'s for it.


Not sure where you are based, but you could try these:

https://www.powerflowexhausts.co.uk/Powerflow-Halifax

They have good reviews.
 
Yes i watched this video.. not sure if i like the metal sound he got with deleting resonator.. maybe it sounds better live. love the bubbles though. Not sure if the car got louder 🤷‍♂️
 
Well i dont have to buy the pipe, my mechanic can make it for me.. so i dont have to spend 500dolars.. that is why i am considering deleting resonator and not switching muffler.
 
Kiashi123 said:
Yes i watched this video.. not sure if i like the metal sound he got with deleting resonator.. maybe it sounds better live. love the bubbles though. Not sure if the car got louder 🤷‍♂️
Yea I know what you mean, I think some of that is to do with the recording of the sound but if it does get annoying for me then I'll just have to get the back-box done as well
 
Better off..imho..with a sports cat..still pas emissions but makes a nice baritone noise not a shot down zeppelin diesel..helps motor breather…another 5-10 BHP..not as cheap as destroying your silencer..
 
Resonator delete is probably the best and cheapest way to get a decent sound increase. Res is built as an “open y-pipe” design with 2 baffle chambers meaning the air doesn’t have a completely direct flow. See pic.

eIQkyd1.jpg

By binning the res, and replacing it with a y-pipe, the air has a far more direct path out of the car, particularly through the valved exhaust pipe. Explanation below.

The muffler is cleverly designed. The pipe with the valve is actually straight through i.e. the pipe actually passes right through the muffler without opening. This means for a stock car, by doing the golf-tee mod, you’re effectively doing half of a muffler delete. That’s why you get such a noticeable difference. Therefore, by combining the resonator delete with the golf-tee mod, your valved pipe is effectively a straight pipe the whole way from the cat.

The other muffler pipe follows a more convoluted and indirect path. You’ll find the majority of the exhaust comes out of the valved pipe regardless of whatever exhaust mods you have done (especially if you have binned the resonator). See pic below for flow:

EmIgtXf.jpg

I’ve done a few exhaust mods, starting from welding up perforations etc in the resonator and muffler (absolute waste of time and made next-to-no difference). I’m now running a resonator delete with a slightly modified muffler (modified muffler makes no difference though, I might revisit that later on). If I was to advise on purely a sound basis, I’d probably bin the resonator first, and then either the muffler or get a sports cat (obviously a sports cat will give a small performance increase, but will be more expensive than binning the muffler).
 
Felixlamb great reply! Thank you!
So what you are saying.. easiest and cheapest way for me is resonator delete plus golf tee mode, to have valve always opened in muffler? Might actually do this!
But what about performance? Some people say exhaust needs back pressure.. so with golftee mode and resonator delete no more backpressure .. wouldnt want to lose 10-30hp because of this.
 
Kiashi123 said:
Felixlamb great reply! Thank you!
So what you are saying.. easiest and cheapest way for me is resonator delete plus golf tee mode, to have valve always opened in muffler? Might actually do this!
But what about performance? Some people say exhaust needs back pressure.. so with golftee mode and resonator delete no more backpressure .. wouldnt want to lose 10-30hp because of this.

With a turbo engine the less back pressure the better… :driving:
 
^ What B21 said. With a turbo, the less restrictions in the exhaust, the better. You want that turbine up to speed as quick as possible. That being said, you probably won’t gain anything by removing the resonator. Perhaps you might get 1-2hp at a push? Main restriction in an exhaust is generally the cat, which is why B21 recommended the sports cat, as you’ll gain not just sound, but some power too. But it’s also more pricey.
 
I saw on other posts i dont need this golf tee, that i just switch off / disconnect something in trunk and valve stays open. Does anybody know what i have to disconnect? Maybe a picture?
 
Jay-Jay said:
I'm looking to do the same and have researched a bit, I was looking at mid box delete like this video:
https://www.youtube.com/watch?v=963Or1nGAcQ

From others that have done it you wont get drone on motorways and it is a little louder, I'm just trying to find a decent custom exhaust garage to do the work and save the £'s for it.
Any engineering shop can cut it out and weld a piece of pipe in...
 
Kiashi123 said:
I saw on other posts i dont need this golf tee, that i just switch off / disconnect something in trunk and valve stays open. Does anybody know what i have to disconnect? Maybe a picture?
E89 exhaust valve is vacuum operated. Simply unplug the vacuum hose from the valve, and plug the pipe and valve to stop any dirt getting in, and you’re done. Newer BMWs use electronically controlled valves - in which case they can be coded out, unplugged (which gives a fault code iirc) or the fuse unplugged.
 
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