TXLSS

Going w/ true duals (2.5") However, car is my daily driver, and I want run cats (prob. dyno high-flows) I know to get the front extensions, but should I get rear sims? Or should I get another, longer set of extensions for the after cat sensors? I don't want to throw any codes, and I don't have easy access to a tuner or LS1edit. This is my last question before I start ordering all the stuff - headers, xpipe, tubing, cats, mufflers, turndowns etc. I tried a search, but seems that every body running true duals are doing so w/o cats. I still need to pass emissions (TX) Thanks for any input.

pimpmaro

I'd get rear sims... the rear O2s are only there to measure the performance of the cats... not needed IMHO.

y2k_ta

iTrader: (80)

You won't need extensions for the front 02 sensors. They should reach the front two locations on your headers just fine without any lengthening. You will however need extensions for the rear two regardless if you use 02 sensors or sims.

BlackWS602

Sorry but this is wrong.

If he is running stock manifolds, then no he won't need front O2 extensions. If he is running LT's then yes he'll need front O2 extensions.

Now you DO NOT need extensions for O2 sims. O2 sims are a small box that just clip into the O2 harness.

Also don't bother running rear O2's if you are changing the position or style of cat. You'll be running a high risk of setting the SES light anyways. Just do sims or get the rear O2's turned off via Edit.

Colonel

What he said.