I've got a B16a in my '88 CRX and a chipped PR3 ODB0. I want to go to ODB1 so I can install Hondata. I know I need a P28 or a P30 but which should I get?

 

Get the P28...waaaay cheaper, tons of people use it with success. Yes, the P30 has a knock sensor input, but the knock sensor is pretty worthless unless you have something that can really react to knock (like a J&S Safeguard). The stock ECU ignores the knock sensor at 5500 rpm and above. Honda did not intend for the knock sensor to be used as a tuning device.

Sonny