This post is for everyone who says that if you round off that nut you have to take it to a muffler shop/speed shop. I recently purchased a MAC X-Pipe. When I went to install it I found that the lower left nut on the OEM H pipe was rounded beyond belief (see picture below). I am not the orignal owner so this came to be a surprise to me. The guy I bought my 00 GT from was in his 70's and barley drove the car. Well since there was nothing to grab onto using a socket or wrench was out of the question. I decided to buy those sockets that supposedly grip rounded off nuts. Those are such a waste of money. I found that out the hard way. All those sockets did was shred what was left of a decent surface on the nut away. So I then came to the forums and looked for any advice I could find. The only advice I found was take it to a shop and have it done. Well it amazes me that for some reason it only costs many of the users here $20 to have the nut removed. I took my car to 7 different places including a family friend and nobody would attempt to remove the nut for anything under $100. Well I decided there were only three options left because I was not going to throw cash away. My options were to cut the stud off, leave everything alone and sell my x-pipe, or chisel the nut off. Well 4 hrs of hell I finally got the thing off. I found if you remove the right front wheel and inner fenderwell you can get to the top of the nut. I heated up the nut and tapped the very top of the nut with a chisel. I repeated the process for a long time without damaging the stud. After hitting it enough the nut broke free and all I had to do was twist it off. If anyone else has the same problem I did give this a try. Since putting on my xpipe I have put on 3 others for friends. Each one had similar problems and each time my method worked. If you have any questions feel free to pm me.