Dude, r u driving Wira, Satria or Iswara?
IMO open-pod airfilter not a good mod for Iswara coz it sucks too much hot air, better find the replacement air-filter (eg UFO-shaped K&N filter), that might be why u don't feel any improvement.
BTW I drive Iswara, I posted what I did (including dyno chart) in The Garage section (older forum version) but since it seemed to have gone, I just list down what I've done :
- K&N replacement airfilter (use back stock airbox)
- Powerzone camshaft
- Powerzone extractor
- Exhaust pipe enlarged to 1.75 inch, with Wira muffler
- Engine head P&P by Powerzone
- 1.6 clutch
- Mikuni twin-choke carburetor
All these increase the power by 30-40% (proven on dyno). Not bad eh, 1.3 Iswara play with standard 1.6 cars, can even chase Gen2 on highways :)
If u're serious to mod ur 4G13 to the extreme, u can :
- Upgrade the engine block to 1.5, and then upgrade to 1.6 (can do with Powerzone stroker kit)
- Blue-print/rebuild, then balance the engine for optimum condition
- (If u'r engine is carburetor) upgrade to fuel injection
- Racing camshaft (280 degrees and above)
- Quad throttle bodies (or twin Weber for carburetor user)
- A fully programmable ECU eg Haltech/Microtech to fully utilize ur race cam and quad throttle bodies
With this, ur 4G13 (with proper tuning) should be able to produce at least 150 horsepower, and rev to 8000RPM. I'm planning to do all the "extreme mods" I listed above.
Might as well transplant a turbo engine at this stage :p