It's definately way easier installing the off road pipe than the cat pipe - I swap them every two years to pass smog. BTW I passed smog with astounding results on Californias new dyno-smog machine for my first time.
"Congradulations! Your vehicle passed the enhanced Smog Check Inspection, which helps California reach its daily goal of removing an extra 100 tons of smog-forming emissions from the air. Thank you for keeping your vehicle well maintained"