wow great question, i remember when i replaced my muffler on my S-10 i ended up cutting out the cat and welding in a straight pipe. i got plently loud after that. lol. i have a co-worker that just removed his dual flowmaster 40 series mufflers and replaced them with magnaflow on his tacoma. i was going to ask a similar question but mine was more geared towards a custom dual. i was thinking about running a Y off the cat and routing a pipe over the rear drive shaft then 90* back and mount the second muffler around there somewhere. i have access to pipe bending and mounting equipment even fabricating and welding. what do you guys think? any obvious issues that i'm just to naive to realize?