Alright, all this discussion on what mods do what, dyno runs, etc. So list the mod, and what power band it helps in. Use this for future reference and seaching Top Mid Low All Around

In general most mods help the engine from mid to high. I will try to list them to the best of my ability and someone can correct me if I'm mistaken.

1. Underdrive pulleys help all around, mostly noticed in the low to mid.
2. Cold Air intake helps mid to high with the right exhuast setup.
3. Exuast systems help mid to high when less restrictive.
4. Headers, most after market will increase mid to high, low end torque may drop.
5. Higher lift cams will help mid to high hp.
6. Valve springs doen't help performance it just increases your revving potential.
7. Head and intake manifold porting and polishing helps high end.
8. Ignition mods help mostly mid to top.
9. supercharger helps all around.
10. turbo helps mid to top (time spooling).
11. Fuel system upgrades most of the time helps mid to high ( 9 MPGriving:

that's all that is coming to me right now. I'll try to add some more later.

Damn, wow, I can't remember what my mods did! Here's a few-

All-around
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Major tuneup!
Dynomax cat-back exhaust
3.73 rear axle
cold-air intake

High rpm
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aftermarket high-voltage spark coil
B&M 4-3 kickdown kit (for 4-speed 700r4 automatic transmission)

Low rpm
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aftermarket spark plug wires
3.73 rear axle

Mid rpm
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Never paid attention