[E92 M Sport]

http://www.jegs.com/i/Dynatech/329/7...FWuhOgodUy4AeQ


I had something like this on my Mustang to get rid of the Flowmaster drone. Idk the diameter of your current setup but it's an idea.

[Killerfish2012]

Originally Posted by jyeah

Yeah, my main question is if it's shifting the rpm occurrence of drone, where is it shifting to?

I'm considering three options right now:

1) Try cutting and welding only the center muffler (resonator) section in
2) Add back in the secondary cats in addition to the center muffler
3) Switch the midsection pipes back to my stock pipes

The thing was, I had the full evolution system welded when I had it installed because the pipes did not seal well and had exhaust leaks (due to heat expansion) that high temp RTV silicone did not solve.

Yeah, the guy who I bought my active autowerke axle backs from did all that mickey mousing around with the active cat back kit, and nothing worked to solve the drone. Since he ditched his stock cat back, and kept his stock mufflers, he finally welded the stock mufflers onto the active cat back kit, which he had already welded resonators to. This finally made his drone liveable. He then had the active autowerke axlebacks for sale (original kit costs $1,900 retail!). He finally sold them to me for $500! and I had them TGI welded to my oem catback, and the sound is great (deep), with NO drone!

[Killerfish2012]

Originally Posted by jyeah

Yeah, my main question is if it's shifting the rpm occurrence of drone, where is it shifting to?

Depends on where the resonator is located on the cat back. On the oem setup it's from like 1,800rpm-2,500rpm to like 2,500rpm-3,000rpm

Originally Posted by jyeah

I'm considering three options right now:

1) Try cutting and welding only the center muffler (resonator) section in
2) Add back in the secondary cats in addition to the center muffler
3) Switch the midsection pipes back to my stock pipes

Besides being expensive (that's if you're using a TGI welder like you should) and technically difficult, keep in mind all of these things will radically change the external sound of your exhaust. It will not sound anything like it does unmodified. Remember that the original external sound is what drew you to buy it in the first place. You will most likely not like the sound. I was lucky that mine ended up sounding good. VERY different from a normal AA catback, but good.

Originally Posted by jyeah

The thing was, I had the full evolution system welded when I had it installed because the pipes did not seal well and had exhaust leaks (due to heat expansion) that high temp RTV silicone did not solve.

Grab the axlebacks and TGI weld them unto your oem exhaust. Take the serious $ hit, and learn your lesson about exhausts.

[SoFlo_BD]

Originally Posted by jyeah

Well, even sport mode doesn't help that much in LA traffic.

It should, I drive in NYC traffic which is just as bad and really can't complain. I also have the alpina tranny flash which helps too.. It does drone a heck of a lot more in D mode though. Good luck man!

[BigHoncho]

Originally Posted by jyeah

Yeah, my main question is if it's shifting the rpm occurrence of drone, where is it shifting to?

I'm considering three options right now:

1) Try cutting and welding only the center muffler (resonator) section in
2) Add back in the secondary cats in addition to the center muffler
3) Switch the midsection pipes back to my stock pipes

The thing was, I had the full evolution system welded when I had it installed because the pipes did not seal well and had exhaust leaks (due to heat expansion) that high temp RTV silicone did not solve.

I considered option (1) buts its hard to weld because of the angle and also the pipes near the centre muffler are "crushed".

As I said I also tried different configurations with and without cats, stock and race/metal cats... there is no substantial difference in low an mid rpms. Only on WOT you can tell, so keep the stock cats if you want less noise on load or get metal cats.

Go with option (3), it works and it's fairly easy to weld. Keep the muffler in the rear and the link-pipe in the front (right behind the downpipe), thats what I did.

[JAL0988]

Originally Posted by jyeah

Well, even sport mode doesn't help that much in LA traffic.

Well IMHO I think you should just go back to the stock exhaust and do the golf tee mod. Then you can putt some cyba tips on if you want it to look a little better.

[Nguyenhu0106]

hi guys,
I am currently running the BMW performance exhaust with stock cats and DPon a e90 335i.... zero drone.. when your at cruising speed on the highway or city... It's not noticeable at least nothing over stock. the only time it's loud is on acceleration and startup... man it's loud on startup. from the inside with the windows closed and music on, doesn't have to be blasting, you can't really hear the burble and the gargling noises from the exhaust on deceleration... driving with the windows open is a beautiful thing, you get to hear everything.

The golf tee mod has terrible drone @ highway speeds lol He'd be better off just leaving it completely stock.

[jyeah]

Originally Posted by BigHoncho

I considered option (1) buts its hard to weld because of the angle and also the pipes near the centre muffler are "crushed".

As I said I also tried different configurations with and without cats, stock and race/metal cats... there is no substantial difference in low an mid rpms. Only on WOT you can tell, so keep the stock cats if you want less noise on load or get metal cats.

Go with option (3), it works and it's fairly easy to weld. Keep the muffler in the rear and the link-pipe in the front (right behind the downpipe), thats what I did.

Thanks for all the comments, guys!

I'm most likely going with option 3. If not, and I change my mind, I'll just go back to stock and sell the Akrapovic.

Also, I'll be writing a review soon of all the mods I've done so far.

[jyeah]

Quick update, the midpipe resonator solved the drone problem.

Exhaust is quieter, but very enjoyable sounding! :P