I figure that I'll change it up and ask something other than a question about top failure, although I'm already guilty of that. So with that said I'll try to appeal to the roadster audience on y'alls real world experience with the plenum spacer.

This weekend I'm finally going to do some much needed maintenance on my Z. I'm installing Tein Enduro pro plus shocks, struts, h spec springs. New plugs, coils and since I'm "lucky" enough to own a REVUP 4 new cam pos sensors. And while I'm there clean out the throttle body. So with all that getting done I was thinking of doing the plenum space but wasn't sure if theres any real gains pro's, con's. Sorry if its been talked about a million times but I'd still like to hear some opinions.

 

Adding a plenum spacer can be beneficial in that it does a tend to even out the air/fuel flow to all the cylinders. Whether it adds HP is argumentative but if it does it is a minor addition. I have not seen "before and after" dyno comparisons but there may be some out there if you search. Also, more then likely and depending on the spacer you choose, you probably will have some minor hood/strut bar interference with the underside of your hood but that can be addressed in various ways.

 

A plenum spacer will give you a few extra hp's but you won't be maximizing its efficiency without a proper tune.

I've got the angled plenum spacer from Z1. I did all my bolt-on breather mods before getting it tuned.

When you're changing out the plugs, if any of them are covered in oil, then some new valve covers and gaskets are in your future as well.

 

I got about 3.5 HP/TQ at the RW from my spacer.