If I were you and I were hooked on turbo at entry level price, I'd probably go with the SBD kit, maybe with a couple minor upgrades. The design is similar to Greddy's kit, they both use pretty short piping. The turbo is a base model but response looks to be ok - just keep in mind even the twin scroll kits will have 'laggy' transient response. Heck even OEM engineered BMW & Audi turbo motors with hyper responsive turbo setups have a slightly soggy throttle (IMHO). Not the snappy response of NA or a well tuned supercharged setup.
If you're after throttle response and don't care about mega power, how about one of those Sprintex kits? It's around your price range, will give you the transient throttle response you're looking for, and they sound pretty exotic too
