would removal of the strut tower bar effect the Z in high speed even traveling in a straight line? And what are the different bars that will fit over the plenum with the skunk2 spacer?

Sorry, this belongs in the 350Z thread

 

Not really. It stiffens the front end to improve handling, ie. flex in turns.

 

why dont you go with the motordyne 5/16 spacer so you can keep it?

 

It might also be important in a bad front end collision to help direct the engine under the car and to make the front body structure perform as designed.

 

Several braces fit in FRONT of the upper plenum. This way you do not have to wedge a brace between the upper plenum and hood.