| I run an ITG in airbox filter (ie., it fits over the bellmouths) on my 996. This is a simple option on the 996 'cos it doesn't have shower type injectors above the bellmouth - 998's etc with injectors sited above the bellmouth make this type of filter installation a lot more fiddly.
This set up lost 2bhp over no filter at all (also running carbon air tubes without provision for filters) with no obvious dips in torque - just a gradual loss from about 6000 rpm upwards - and was chosen because I planned to race the bike and wanted protection in the event of a get-off (using the tank as the airbox top means an airbox full of gravel is almost guaranteed in any serious 'racing incident'). To my mind this should be a serious consideration for any track-day junkies.
I don't have any data comparing this set-up with standard filters - but if we assume standard filters will not be quite as good as no filter at all then realistically the in-airbox job is probably costing about 1bhp and I defy most anyone to be able to spot a <1% bhp change without the aid of a dyno!
Does muffle out some of that airbox noise though.  |