From those of you who have purchased the Greg Banish DVD (GM EFI Tuning Beginners Guide) did you think it was worth it? Any disappointments? Any other tuning material you recommend? I'm a competent beginner (Did my heads/cam/intake/supercharger/converter/rearend/etc. myself) but I'm new to EFI tuning. Any advice/recommendations you can provide would be great. Thanks!