That modified stock muffler might sound better but it also might hurt the power a little in its current shape. I noticed the exit tube has just had the pipe cut off square. You could pick up a lot of additional flow by adding a radiused entry to the cut entry end of that exit pipe. If you go back up near the top and look at the stock muffler with just the cover removed you can see even the factory added radiused entries to the exit hoops, although they should be much larger and radiused more; the picture below shows what it really needs. This is just to illustrate what could be done to improve any pipe inside a stock muffler, not the end of the entry pipe, it wants to be cut square. This is just for the entry end of of exit tube.
