I am thinking about cutting my cats off, and then gutting the insides....and I can weld em back on. My question is, will the 02 sensors realize what I've done and cause a DTC or driving issues??

 

Yes, the rear O2's will throw catalyst ineffeciency and possibly overtemp codes. The PCM can be tuned to turn those codes off, or you can buy O2 simulators that plug in to the connectors that go to the rear O2's.

 

Where do I buy the O2 sims? And in the end, is it worth the effort to gut them? Or am I just in an old school thought process?

 

If you're gonna be doing more mods to the engine that would warrant the extra exhaust flow, then it would be worth it. You don't want to just gut em though, you want to replace them with straight pipe, then slip the cats over the pipe if you need them physically there for inspection. Just gutting the cats may cause turbulence and not allow the free flowing exhaust to work to it's full potential. You should be able to find O2 simulators at Summit or Jeg's...do a search either here or at Google and I'm sure you'll find more sources to purchase O2 sims.

 

Good point on the turbulence. Thanx.

 

Caspers electronics sells o2 sims. If you get or have a custom tune, just turn the codes off. Its the cheapest way considering the o2 sims arent cheap.