I am going to put a downpipe on a 96 WRX. Have wrapped the downpipe. It has a Lamda sensor drilling at the top, but of course my lamda is in the drivers side exhaust headers. Seems to be going ok so I feel that I do not have to relocate it and risk upsetting it....so do I just blank off the downpipe lamda drilling and simply swap. Can't see a smaller exhaust probe hole on the new downpipe, but the top hole is a 20mm threaded one. It is a H and S downpipe, 3 inch tapering to 2.5.

 

Blank it off

http://www.tsl-motorsport.co.uk/exhaust.html#d

 

Wont an old spark plug do the same thing???? May look at bit crap though