a small question about 02 sensor simulators
 

i have a 2004 cheverolet silverado and have long tubes with a y-pipe on the way. i plan on takin my convertors off and need to know if i need 2 or 4 02 sensor simulators. also will a 02 model simulator work on my 04 model truck.

No sure about model compatibility, but you should only need the rear O2s simulators (2 total). They are the ones that monitor the catalytic converters.

i recomend a custom tune. whoever tunes can turn off your rear 02 sensors to turn the lights off in your dash. they can also tune for the best gains with your headers. check out the nelson link in my sig. he can get you fixed up

I have the caspers electronics o2 sims in my truck and they work perfectly. You only need two simulators to replace the rear sensors...

rear only, make sure to get variable reading ones if you ahve emissions

this is your best bet.
Good luck!