My regular place is in Kota Damansara(Padang Kota area). The shop is called EuroTechnic Motorsports, they do mainly BMWs and I have seen lots of monsters in the workshop.(eg. Crazy turbo or supercharged BMWs) You can give them a try, prices will vary depending on what is found to be faulty in your engine during the strip down. Cost will start at RM3k minimum...
If you need the address you can PM me..
joeylow