so the Civic SI is OBD2, and has 2 oxygen sensors. what type are these sensors, and where can i pick them up for cheaper than the 150 for the set my friend was quoted.....

 

any four wire o2 sensor for a honda will work.

but if he's going to honda, he'll be raped.

 

You can get the universal 4 wire O2 sensor but you will have to cut off the old plug and wire that to your new O2 sensor.

I think sparkplugs.com sells them...maybe even your local Autozone has the universal type.