So I've been doing a ton of research but can't seem to find any information on this. I know Works used to offer this (I don't see it listed on their site anymore, but do see it on MAPerformance). It seems this was effective for the 2008 model but I can't find any info on whether or not the same results would be offered for a 2011 model.

I know they got rid of the flap inside on the 2011 and I've heard people say the 2011+ does sound throatier than the older ones. My question is will this mod still give me the same performance results as the 2008 even with the changes Mitsubishi has made on the 2011+ muffler? I've seen people post up dyno results gaining 8-10WHP with this mod but only on 2008. Has anyone with a 2011 model or newer tried this and actually gained power?

Even some of the sites that are offering this says it's for the 2008 model, not 2008-2015. But I've also seen a site say it's for 08+. Please don't answer with things like "just get an aftermarket exhaust" because that's not what I'm trying to do. I'm looking for the specific answer to this stock muffler mod.

 

http://roadraceengineering.com/blog/...stock-muffler/
^^^this was from a 2013 MR so regardless of what they did in 2011, it can still be modded.

See:
http://www.socalevo.net/threads/2251...-360-awhp-E85-)

 

Thanks Splatt. I did come across that first link you sent from RRE already but it didn't say anywhere that it was a 2013 MR. That 2nd link confirmed it for me. I also got a response from Mike at RRE. He told me to bring it in to see if my muffler has the flap on it. I guess even though the middle pipe is what makes more exhaust flow it's the flap that really makes a difference. From what I'm gathering if you have the flap then removing it is beneficial (like that 2013 MR), but if it doesn't come with the flap then it might not make a difference.

Anyway to find out if my muffler has that flap without having to cut it open?

 

You might be able to get an inspection camera in there but honestly, if you're interested in the mod, just do it. If you look at the flow routing, taking out the pipe section will add a little volume and flow regardless of the flap.