Most cost effective HP+ modifications?

[Steve Tinker]

+1 on the underdrive pulley.
The one I bought from Flat6 fitted perfectly and you can feel the difference in the low to medium rev range where 90% of your driving is....

[Johnny Danger]

Here are some thoughts from a previous thread:

1. A comprehensive and methodical approach to revamping the vehicle's exhaust system; i.e. headers, cats, cat back ect...
2. Light weight under drive pulley
3. Larger throttle body and plenum
4. ECU re-programming
5. Lighter wheels (a potentially faster and better performing vehicle by means of
reducing unsprung weight and rotational mass)
6. Reducing weight in general; i.e. spare tires, oem seats, lighter battery ect.. (this is
more aimed toward tracking your boxster .
7. Suspension upgrades (though not a direct increase in power, a faster vehicle can be
had by means of better handling and performance .
8. Increasing airflow to the engine, i.e. cold air intake or filter replacement
9. A divorce (a major reduction in weight by means of one less passenger, as well as financial freedom to do more mods)

and the list goes on ...........
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