R33 Back Fireing

[hypo31_abz]

why is my r33 93 backfireing... this only happens when i want speed, for example if i want to put the pettle to the metal, its starts to sound lean then backfires not allowing to go on high rev.....

I have took out the blow off valve piping half and inch to its normal puting. but the backfiring never occured when i done this, only after 2weeks.

help would be much appericated

abz