Hey people, just got a hks decat system for my 97 type r, i have fited it, but was wondering, were the old cat downpipe was it has the lamber sensor at the top and after the cat another sensor at the botom, im not sure what this is and the new hks pipe has a bung were this sensor should go.. do i need this second sensor connected? also dosent the larger pipe size mean lose of some back presure afecting performance?
Thanks for any help

 

The sensor at the top, directly behind the turbo on the downpipe is the lambda sensor, you need this.

The sensor after the cat at the bottom of the downpipe is the cat temp sensor, this can be removed from the car as you no longer have a cat

Loss of back pressure on a turbo car will result in an increase in performance ans the turbo can get the gasses out quicker.

Enjoy

Paul