my 2 ltr is running fine ive allways wanted twin webers so i bought some dual 40mm plus manifolds for kombi ready to go then i asked volksbahn how much to put on and tune
leanne said i should justify the motor work to need these
for the extra fuel/air to power the motor ie cam etc ?
what sort of work would i need to give her"my bus" extra grunt and to handle higher revs doing say 120kms without stressing her out ,plus be reliable?

Much depends on the actual sizes of the chokes installed into the carbs.
What size are they? this matters the most as the "40mm Webers" does not say anything.
You can have those 40mm carbs with 28mm chokes, plenty bigger or even smaller if you can get them. It all depends on the original installation and what revs they were asking of it.
As far as mods to the engine to justify the "extra air and fuel"?? Your engine will still only demand the air (and fuel) it is currently capable of asking for now and the carbs (if jetted correct enough) will meter fuel according to the current demand.

Any reputable dyno mob can set your air/fuels to get it driveable enough.

With a bit of farting around, you can make a pair of 48mm IDA Webers run ok enough on a bloody ride on lawn mower so dude, fit your carbs and have fun with them, boast about them to your cobbers and add your trick bits next time you bother to remove the engine and strip it.
L8tr
E:thumb

Ummmm.... i asked her a few questions..........once.

There is ALWAYS a circle in motors.
What cam
What heads
What "combo!"

You have to start some where and dual Webers are a good add on to a stock 2L T4.
LOTS of people have done just that.

I would take it to some one like CBB or VVDS. Mike has the Dyno at CBB and Boris will do it as well.

Maybe even CSC at Burwood (near bus depot)

You WILL need to change things - vents etc.