Why is there a exhaust bung on the header and then one on the down pipe infront of cat. only one (O2) is being used.

is the other for sensors like AFR or what?

is there any advantges to using the other bung?

 

bump

 

Might as well ask this while im bumping.

anyone know if my D15B would pull harder with y8 head or with stock?

If stock, then should i swap out gaskests for compression?

 

I think the d15b's head has a more aggresive cam than the y8 so keep what ya got. and sure swap out for the y8 gasket cuz you can remove the layers and bump up the compression, but that sounds troublesome for 5 horses. AND (uuu i started a sentence with and!! im gonna get reported) the second bung ehhhhh i can only think of a heat riser which i doubt.