I have Brembo discs and pads on my 3.5 and whilst they are okay, the set up is not that good but it’s more about the size of the discs and calipers as they are very small!
Performance fluid and stainless brake lines would help but not enough alone if you need more braking performance.
I am looking at what physical upgrades could be done using other Toyota fitments as something like the 4 pot calipers and discs from the ST205 Celica would be a great upgrade…
I have seen an AP racing upgrade but that was over 4k so not really in budget unless you are going down a Trackday route!