The B230F isn't a really hot-roddable engine, not on a budget anyhow. Minor gains can be attained with exhaust and camshaft changes, but you're really tweaking either low-end torque or top-end power, rather than giving a substantial across-the-board increase in power. The rev-limiter, integrated into the ECU, restricts the practicality of tuning for high-rev potency. Bolt-on gimmicks like the electric "superchargers" sold on Ebay are just that - gimmicks. Turbo is the way to go for the best HP/$ ratio. Still not cheap, but by doing your own labor & buying a crashed donor car, you could likely do it for under $1000... and likely make that back parting out the donor car, and selling your old motor.
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Chris, Dartmouth NS Canada 70 M-B 280SE, 83 245DL, 84 244 turbo, 90 780 turbo, 92 VW Golf, 90 740 Rex/Regina