yes.... i have done GHB numerous times with HPPD..
It is a depressant not a stimulant... therefor does not seem to exacerbate visuals as much as something Like MDMA...
Just be careful as how much u take because it is easy to drop, unconscious, coma etc ... i have experienced overdose before...
Whilst intoxicated, i like the effect more than other recreational drugs, due to the fact that other stimulants intensify visuals from HPPD...