I'm in the process of installing a set of used Staintunes on my 907. The chip has not been upgraded. What about the airbox? What should I do to increase airflow, etc. Wayne
1992 Paso 907ie
2002 ST4s

I bought my 907 with Staintunes fitted.
There are no mods to the airbox necessary.
Take care if you try to modify the airbox - the 907 and 851 use the airbox vacuum in the EFI setup - so you can't just chop it up willy-nilly....in fact I have a post dedicated to misfire related problems that strongly indicates the importance of the air box vacuum...
Mine was chipped [Ultimap] but it was necessary to get a chip that was set for Staintune exhausts. This chip is an Ultimap, too...

something to take care of is swingarm clearance at the footpeg exhaust mounts.
The Staintune bracket chewed up my swingarm - they are very soft & easily damaged..
The exhaust mounting brakets can hit the swing arm during loaded riding / bumps..
It looks like there is plenty of clearance when the bike is unloaded or up on the centrestand when the swingarm is at the bottom of travel - this clearance is reduced under load.

Get some friendly fat asses to sit on the bike to check clearance...don't forget to allow for some lateral flex and free-play when you consider the clearances...

Personally I think the Staintunes are OK but ugly...and have considered hack-sawing off the ends plenty of times....in fact I might do it today!!!