i recent got the Trust (Greddy here in the states) AirinX large mushroom filter, and i must say... it kills the VTDA in perf. and price. as opposed to the K&N cone, the shroom type filter can BREATHE better. i noticed a slightly better pull/throttle response throughout the powerband than the K&N.
another bonus is the funnel adapter it comes with(diagramed below)
alas, the filter's louder than the K&N cone. the only downpart is the fact that it's a dry element filter and instead of cleaning the filter, you gotta replace the element for $15... which isn't too bad imo. for $50, you really can't go wrong.
so long VTDA, you were once loved. [&:]