I'm considering going with a 4 port Mega-Oval muffler from WWW.stainless-specialties.com Was checking out their mufflers construction at Charlotte Motor Speedway. Sounds deep, mellow and not overly loud on a V-8 with their single 4 port design. Any muffler will be louder if you install two seperate singles. Sound can sometimes be tricky coming from a 6 cylinder like ours! I would think the four port would fit well under our cars with the rear cats removed. Finish out from this muffler with true duals. They also make up a stainless dual inlet welded into a nice looking box that looks better than the porshe boxster's exhaust tip. 4-Port dual muffler> 2 1/2H X 6 1/2W X 23" LOA. Custom sizes are avaliable.. Squirrel Crusher