Don't worry about stage charts. Most of the time they are from manufacturers using their own products. For example a JWT stage chart for the Z32 is different than the stage chart from say HKS. The only thing stage charts are good for is if you plan to only use one company for parts. Since there are no compaines that make bunches of parts for our cars there are no stage charts. Anyone can just make one up but it would be different from one someone else makes up. Stick with the basics like intake and 3 inch exhuast from the turbo back as your first mods. Intercooler and boost controller as the next mods. Basicly you have to do these things first as base mods. After that it's whatever you want to do and talking with others to see what works. The Z31 and 280zx don't exactly have an aftermarket following.