If I ordered an upper plenum would I still need a spacer to maximize the performance? Which upper plenum is the most popular? Will I need to get a different strut tower bar with an upper plenum?

 

Welcome. Aftermarket Upper plenums have shown a terrible dollar/horsepower ratio.

Some members have combined aftermarket upper plenum with a spacer for pathetic results.

The spacer alone is a winner. Which one? Read. Will the spacer that you buy clear the strut brace? Don't know.

 

Unless you have a considerable amount of engine mods and/or tuning done, you won't notice much with just the upper plenum. Until you get some mods under your belt, stick with just a spacer. As for most popular? Crawford, Kinetix.

Most 5/16" spacers will clear the strut bar. 5/8" and up will not.

 

Don't combine a aftermarket plenum with a spacer. The aftermaket plenums are designed to use all the space available under the hood.

If you add a spacer to it, there is a good chance it will come in contact with your hood.