i know everco, sunway can do custom made extractor.

the extractor is the most sensitive part in the engines breathing system. i wouldnt recommend ANY custom extractors no matter what they say. this is because if its wrong then ull end up with crappy power and be disappointed. stay away from them man...seriously. i would only recommend performance brands extractors or stock extractors... thats it.

as for the air filters... heres the thing....

open pod's advantage is that it sucks more air coz its open and able to suck from all over the place around it. while replacement elements in an airbox is restricted suction because it sucks air from one source which is the hose..

best solution would be to combine both... get an open pod, make a custom air box for it... and shove in many many many many (mebbe 2 or 3 big ones la) hoses into the air box from the front..... this should give massive amounts of air....and more importantly...massive amounts of COLD air.

@kev da man
simpler yes, but heatshields only reduces the amount of hot air being sucked in...

the way i stated will ensure ONLY cold air is being sucked in. or at least whatever the air temp is outside. time consuming? errr...depends on how elaborate u make the box. u could always use those chrome windscreen sunshade thingies to make a heatshield + airbox (2 in 1) with those hoses. as for how messy it is...depends on the car actually...placement of airfilter, where to direct the hose etc etc

It's not about the exhaust being restrictive. This is a common mistake among people, back pressure doesnt contribute into producing more torque.

Actually, smaller exhausts leads to a faster exhaust gas speed(Bernoulli principle). When the exhaust is traveling out, it leaves a pocket of vacuum behind it. This pocket of vacuum makes it easier for the next pulse of exhaust gas to go out(less restriction). But this only works if the gases are in pulses(like in lo revs). As the gas moves out in a stream(higher revs), its useless so bigger exhausts produce more power.
Just as an example, have you ever thought why exhaust pipes of a bus is small?

bus of coz la... their engine so high displacement... duh~!!!

exhaust pipes are bent in certain ways to induce backpressure... so u can feel abit more torque at low revs... but too much backpressure will cause restriction and will decrease horsepower....