1. both the same head.
2. plumbing a cold air intake in a high pressure region with a ram funnel profile is a form of speed dependant forced induction. end result is slightly more performance only at high speed.
3. the engine is only as good as the weakest link of the progressive chain.
imo in N/A you hardly reach the flow limitation of a panel or cone filter for it to become a major restriction of the rest of the system. there are more restrictive parts of the system further down to better spend money on, such as the narrow TB, log casted inlet mani, hot coolant lines through the TB, inlet mani being heated by engine, very choked exhaust mani, etc
another thing is inlet temp.
panel filter airbox, you can enlarge the inlet port & plumb a CAI for a cold supply.
a pod filter, you have to heat shield the filter to keep heat & debris away and locate the inlet port or filter at a cooler region. pod filter without shielding and/or cold air supply will simply suck hot air and degrade performance and reliability.
4.
a - have the best starting platform to begin with. upgrading 1L to 1.3L engine is an easy direct upgrade from 55hp to 75hp but may affect running costs ie tax & insurance.
b - ensuring its the best engine condition to start from. ie the best low milage good condition engine with the least blowby, good high oil pressure, perfect cam timing closest to original spec.
c - then service & ensure the engine is operating close as possible to the original spec (fresh oil, coolant, filters, clean injectors, clean & gapped plugs, all sensors & control valves clean & working perfectly).
d - then we begin upgrading. few examples include reduce any weight, CAI, enlarged airbox inlet port, bigger TB port, removed TB coolant lines to keep it cool, inlet manifold teflon spacer, 421 manifold, decat.
e - the last step which may not be cheap but allows u to unleash the most potential out of all those mechanical engine mods listed above with the most reliability is to remap the ecu.
