im pretty new to this whole petrol boost game. fitted a boost gauge to my S3 last week because it just doesnt feel as fast as it should be (bearing in mind ive never been in another S3) and its boosting up to 10-12 on full boost, but sometimes in 3rd it will boost up to 20psi! then drops all boost and boosts up again to 10-12psi. also when i hold it on mid boost it makes a hissing sound, as if there is a boost leak some where, or the dumpvalve cant hold the boost. as ive heard the standard DV being plastic is prone to failing. its also only reading 5 on the vacum side when on idle where as im pretty sure that should be on 20. if anyone could shed any light on my situation that would be ideal. if there is anyone in the Portsmouth/ Southampton area that could maybe take me out in there S3 or be able to give me some advice on this that would be amazing!