Originally Posted by kozi2013
What's the best for an occasional race but not to overkill?
Nitrous with all the proper equipment and a damned good tune.
Roots Superchargers (Magnusson/TVS/Eaton/Whipple) have an almost flat torque curve. Can be limited on boost levels due to efficiency of the supercharger/pulley availability/room under hood and cowl for a stack intercooler/heat exchanger. These can make a crapload of torque. Regular OEM companies have run these on production cars because they're relatively low maintenance.
Centrifugal Superchargers (Procharger/Powerdyne) are geared and step up the boost as rpm climbs. Higher maintenance than a roots, requires a rebuild a lot more often. Unless you find a direct fit kit, you're going to need to do a lot of fab work on a bracket/pulleys and routing the belts correctly.
Turbochargers have a wide selection to pick from. Choose wisely. You do in fact get what you pay for. If you talk to a distributor that is familiar with performance applications for turbos, they can just about nail down the best for your "need." They require a good bit of homework and fabrication work, even with direct kits from people like APS or KY Speed for the LSx kits, etc.
With any of these power adders, you get greedy with the boost level or the nitrous and it'll break it's foot off in a spot where the sun don't shine. You have to do it progressively and understand the weaknesses of your build as a power adder will find those weaknesses and tear a big hole in it.