Its not just about peak dyno numbers when testing,
I am tyring to find Tophers thread when we tested the Pipercross venom kit, the peak numbers where poor but the logs told another storey.
Its not an easy question to answer.
Modern cars are load based ecus which in short mean once the car see the correct amout of air flow to produce stock power the ecu will cut back throttle angle, timing and load request. But then we have a stock R32, remove the air box and just run with the maf and you will see 12bhp gain on the peak power, and around 6bhp with a panel filter. NA cars get the best gains from filters.
An LCR BAM stock air box and Pipercross filter is limited to 247bhp at which point the airbox and filter becomes a restriction.
The BMC induction kit on a 1.8T can only flow upto 213bhp tops, just by taking the BMC off and adding a cone filter you can find 15bhp.
A stage-1 AUM can gain around 4-5bhp on peak power with a Pipercross panel filter
A civic type-R will get an extra 14bhp at points on a dyno graph with an k&n induction kit.
Some TDIs lose peak power with filters.
