mate if you can get a st 1 and st 2 air filters and a power commander it sorts it like a dream, mine was a 04 had the same prob until i did this.

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TITAINIUM CCC,STAGE 1 K&N,STAGE 2 DNA,PC3, CRASH BOBBINS,SNORKEL REMOVED,HANDGAURDS,BASHPLATE,CUSTOMIZED REAREND,NITROGEN FILLED TYRES.