Was out enjoying the nice weather earlier when my car started playing up, engine is running fine, so smoke, turbo sounds fine and boosts as it should, but stops boosting at 5 psi, when it usually boosts to around 20. I'm not that clued up with turbos, so I'm not sure what things to check? There's no warning lights on, all the hoses I can see look fine (would have to take the bumper off to fully check them all for leaks).
Suggestions please . Ta