i would just buy a ings+ wing. You don't need a wind tunnel to know that you have downforce right. When you're racing you could feel it. They test their stuff in actual race series so I'm sure it does something.
https://nextlevelperf.com/?s=ings%2B...ct&dgwt_wcas=1
as for spoilers i dunno, probably stick with a wing for race focused build imo
https://nextlevelperf.com/product/in...ssan-370z-z34/
"The INGS Japan Ver.NISMO wing is track tested and proven in the Super Taikyu racing series in Japan. With multiple wins the ASSET INGS team have developed a functional aero-kit born of competition. Featuring Hybrid Aero to provide a strong and rigid yet impact resistant material.
The Ver.NISMO wing comes standard with 1515mm width single or dual foil option. In addition to the great contribution to the driving performance, the wing prides itself on the bracket made of dry carbon material and on the metal supports made of machined aluminum with excellent texture. The brilliant craftsmanship of INGS is represented by this product."
fwiw.