HKS VPC do work very well - I have no personal experience of using it but if you check the dsm sites a lot of guys use it.
http://www.dsm.org
http://www.teamnabr.com
http://www.buschurracing.com (Dave Buschur uses VPC on his race car)
Also Bozz Speed use VPC on their 500hp Lancer Evo 5
http://www.dsm.org
http://www.teamnabr.com
http://www.buschurracing.com (Dave Buschur uses VPC on his race car)
Also Bozz Speed use VPC on their 500hp Lancer Evo 5