I have recently purchased a 1984 900 16v Turbo which is reletiveley standard....It has an old sports exhaust, one of early twin flare types and sports shocks of some kind however I'm interested in improving engine performance. How easy is it to control the APC to increase turbo boost? Keeping in mind the engine is standard is this advisable? Whould a dump valve increase noticable power? I'm a complete new comer to Turbo engines and any info would be great.