Just got my car tuned yesterday and ran into spiking problems. My tial 38mm wastegate has a 1 bar (big Blue) spring in it. I wanted to rev it to 9k rpm @ 15psi, but instead, it spike to 18-19 psi @ 8k rpm. no boost controller. My set up:

Built gsr
precision sc61 with s cover
thermal 3 inch exhaust
neukin manifold
neukin downpipe
open dumptube
hondata s200b

Is it that my turbo is big???

 

anyone know what it might be?

 

Try a softer spring like a 6-7psi, if that doesn't work your gona need a bigger wastegate.