Here's a Cool supercharger kit that will let you spend about $2,000 and double the HP of your 1600cc VW engine. Kopressorhaus makes an AMR 500 Supercharger kit for your VW. Here's a cool kit for your 12001900cc engine,. It'll add up to 50HP they have 3 versions. "The Sleeper" an under deckled that uses a HD the carburetor. "The Ultimate" is the Kit that uses a dual 40mm DCOE side draft. Then "The Cyclone" uses a down draft 40mm Weber this is for uses in BAJA bugs and dune buggies and does not fit under a deck lid.
Check them out here https://kompressorhaus.co.uk