You didn't mention your catalytic converter. On my 04.5, i eliminated the muffler and left the cat for a while, then i decided to go complete straight pipe and i am so glad i did. With no muffler and the cat it was loud, but not bad and not quite as deep as you typically hear. When i removed the cat it got a lot louder and deeper and i love it. Just remember to roll up the windows if you have a phone call and let your foot come up just a tad.

 

DIY? its not easy gettin the muffler off. take it to a shop. muffler delete pipe was 50 buks and install was 60 buks. Sounds awesome. o ya and order a stainless tip for it too. good luck