So after reading and thinking that some people have run the 9th gen Si axleback on their non-si I have found that this part: DOES NOT FIT. 2012+ Si Axle back does not fit the R18. Not direct bolt on anyway. The 2006-2011 Si axle back does fit. I'll explain how later. For now... How to get the 2012+ SI axle back on your R18: First off the flange on the end is completely the wrong size. I had thought the possibility to drill the flange existed but as you can see that would require drilling into the area where the gasket sits, & there is not enough material to drill towards the outside either. It's not even close. So what to do? I took both mufflers down to the local exhaust shop and had them cut the flange off the current R18 muffler and cut the flange off the new Si muffler. Then they welded the old one onto the new one. They did a pretty nice job. I gave them a lot of freedom and said "just make it work." I didn't care where they cut/welded whatever. Here's the results: They managed to get it right on the end and only transferred the flange.They said it was a little tricky since it was so close to the bend. Not the cleanest weld but they did it for me in an hour while I waited. So now it should bolt right up to your R18. Reuse your old gasket and hanger. You may have to bend the tangs to get perfect fitment under the bumper. Also reuse your hanger. Thats the black rubber thing you see in the picture on the tangs. Install is 2 bolts and a hanger. I'll try and get pics when I do this in the next couple days. So how much did this cost?? That's the real variable. Option1: 2012+ Si axle back: Requires modification. You will no longer have your stock muffler. 2012+ axle back - $100-150 used Welding - $depends on the shop you go to. They charged me 1 hour labor $86. Total so far: $246. Option 2: 8th gen (06-11) Si axle back: Direct bolt on fit. Find a 2006-2011 SI axle back. Usually $100-150. For this to work you need a new 8th gen Si muffler gasket. About $20 Part number: 18229-S7S-003 Possibly a couple 5/8" washers to space out the spring bolts so they don't rattle. nat3d has an 8th gen axle back on his 9th gen R18. Total: <$200 Option 3: Borla Non-Si Axle Back: Borla makes a direct bolt on for the 2012+ R18 Part #11828 Wesellcarparts has it. It looks nice but it is costly. http://www.wesellcarparts.com/store/scripts/prodView.asp?idProduct=9814 Total: $400-ish! Option 4: Megan Racing Non-Si Axle Back: Same as the Borla. http://www.wesellcarparts.com/store/scripts/prodView.asp?idproduct=9833 Total: $400+ Yikes! Option 5: TSUDO cat-back system: Yes, you can get a full cat-back tsudo for the EX/LX for less than the cost of the Borla or Megan muffler alone. http://www.erzperformance.com/Tsudo-Honda-Civic-DX-LX-EX-2012-2013-Coupe-or-p/20-9376.htm Total $330-ish I think Injen has an axle back that should be available at some point but I didnt see it available yet. Let me know if you have questions. I'll try and get the install done this weekend. Ill post the update here.