I am wondering what is the little sensor thing for the exhaust is for... I am thinking about taking off my catalytic converters and either get the cat replacement from RB or go to a muffler shop and get a custom pipe... I don't know which one to pick because the RB one have the extra piece for the sensor http://racingbeat.com/resultset.asp?PartNumber=16203

 

its an 02 sensor bung, its used with ecu's and measuring widebands, if you have a carbed engine and no wideband of somesort ... you can just plug it with a bolt

 

it is not a o2 sensor bung.......it is for emission .. i beleave the aire pump hooks to it..if you have removed all the emissions i would just have a muffler shop make it for me with out it..if you still have them seeing as your in ca get the racing beat 1 and keep your cat and swap them out when you have to get tested

cheers PaTricK