To start off, i have a 98 V70 AWD LPT with the following mods: Snabb intake, 16t, R manifold and a solid stage 0. I have been running this setup with a 98 R ECU with no trouble at all. I installed the ARD ECU (Orange) tuned to 15psi and set my waste gate to 3.7 psi per instructions. I followed the ECU learning procedure of accelerating at 25%, then 50% and 75%. It is here when I run into issues. When in boost above 3500 RPM and boost gets to 10psi, the boost shoots up to 18psi. I guess the ECU tries to cut off boost and the I get this boost on, boost off, boost on, boost off. So it surges and cuts back and repeats until I let up off the gas. Is this boost overshoot due to the TCV being slow to react,or the spring/diaphragm in the turbo not supporting the boost? I'm looking for any help or advice to correct this. Thanks for any and all help!