from what i gather book figure on the 2.5 WRX is 227bhp so i was surprised when i got these results after a dyno run with only an HKS panel filter and a £150 mandrel bent ebay (toyosports) 3 inch catback.



so what im wondering here is does the 2.5 WRX tend to put out above book figure standard (or have i actually picked up nearly 30bhp and whatever torque from a panel filter and catback?) and how do the numbers above compare with others who have dynoed theirs with similar mods.