Looking for opinions on resonators for my setup. To install one or not and how necessary a name brand is or not. Wondering first of all if one is even necessary for a turbo vehicle? My exhaust quieted down substantially after I went NA-T. And I know a turbo wants no back pressure. Do they even make a drone noise that I should be concerned about? Or does a turbo keep enough flow going to stop drone? And are they all about the same or is it worth paying double for say a Magnaflow?

My reason for asking is that I will be changing my exhaust soon. I still have the 2.25" Megan mid-pipe right after my 3" down-pipe (It has a very small resonator). And that goes into a 2.75" (ebay) exhaust system with a factory style duel pipe. (splits shortly after the mid-pipe and goes back both with their own muffler.) This system does not have resonators. Just mufflers. The drone was bad when I had the N/A headers. But I have "no drone" now with the turbo.

What I want to do is go 3" all the way from the down-pipe with a single outlet on the passengers side. This is to maximize flow and shave weight. My original thought was to put in a 3"in/out resonator and 3"in/out muffler. I don't want the car to sound bad. But I dont want to put a resonator in if it's not necessary. Cost more, and dead weight if it won't do anything. I just noticed that all drone went away and the overall tone/volume lowered by a lot. So basically I'm asking, do I need a resonator if all I have right now is the little on on the Megan mid-pipe and currently no drone? I will be loosing the Megan mid-pipe's small resonator and one muffler from my current system, plus increasing system size to full 3". So on the flip side would I likely need a big resonator and big muffler to make up for these changes?

My planned muffler and resonator are Magnaflow: 14834 and 14419 (3"in/out)

 

I know that this doesn't answer your exact question about the resonators and you'll have to look back through some old threads but I think at around your 300 whp you won't see many benefits from an exhaust over 2.25-2.5". I remember reading some very old posts from somewhere between 2008-2010 by jefftsai where he was talking about exhaust size and restriction. He went to a 3 or 3.5" exhaust once he was around near the 5-600 hp mark and then 4" up around 8-900 hp as the exhaust was becoming a restriction. Just a thought that unless you're planning on adding a lot more boost it may not be worth it to go with a bigger exhaust than what you have now.

Wish I could help you more than that and I hope someone else chimes in

 

Yes I am planning to work up to 450-500 after a thicker head gasket and arp studs. Some head work/porting too. So the exhaust will be more of a getting ready for that kind of thing.

 

that turbo needs to expel the exhaust gases as easily as possible. thats why some guys run 4'' downpipes right off the turbo. the easier it is to rid the exhaust the quicker the turbo will spool and continue making power. just go with the entire system at atleast 3'' and than see if it drones. if it does, than buy a vibrant fat body resonator. itll flow straight thru but will absorb alot of those drone frequencies.

 

I’m taking it to a guy a know in another city that does outstanding work and welding. I don’t really want to have to take the car back if it does sound bad and pay again for a resonator install, plus order it in and wait for it if it needs it. So I’m just gonna order the two items I meantioned and have them installed now that I think about it more. It won’t hinder performance and better safe than sorry. Found them both a little cheaper on Amazon/eBay today anyway. Thanks for the input guys. I’m also going to have two v-band flanges put into the system similar to the one coming off the turbo to the down pipe. One where the downpipes meets the exhaust under the car, and one closer to the back to make system removal easier for future plans.

 

I don't suppose anyone has seen a rear bumper on a GS with only one exhaust notch? I haven't even found any images, let alone a purchasable part. I plan to fill in the notch on the drivers side if there isn't anything available. Blend it in nicely.

 

Theres a build thread on the forum where someone did exactly that and filled one of the holes in the back bumper. I have no idea who it was though