High flow cats question....
 

About how many miles do you get out of them before they get clogged up? How do they sound compared to the stock cats/off road h-pipe?

There is a big dif. in sound with an off road pipe. I had my long tube headers with the hi flow cats when there was emmissions, then went off road H pipe after they stoped testing. I gained 7 HP on the dyno at the wheels and it sounds soooo much meaner at WOT. I do have 3 chamber flows though, so they quiet the car down too. Hope this helps