<VV> tech questions

[Bruce]

A couple questions for those of you who are much more "Corvair savvy" than I . 
 Can anyone tell me the advantage , or function of a crossover pipe used with dual exhaust?
   And, should wire wheel hubcaps( orig. option 1963) affect wheel balance ? wheels were dynamically balanced without the hub caps on.. 
 Also is there any upgrade/ improvement / aftermarket product for the rear ( and front)suspension on a 63 (vert)  thank you.
...,Bruce