my wife has a 99 sienna. its great but very soft in the turns (just like the camry). i know the vehicle is designed as such. can i change struts, shocks and rim tire combo to give a more sporty/safe feel? or, is this a waste of my time?

From what I have heard, the Sienna is on a camry chassis so there probably is something you can do for it. I know you can at least get new wheels...My mom's Sienna feels the same way, BUT it sticks really well and I could take turns faster in it then my buddies could in their Audis and Chevys, hahaha. Imagine their suprise.

I added Airlift 1000 airbags to rear springs of our Sienna to help with rear end sag (of the van) while towing our pop-up trailer.

The side benefit is that the van handles much better while not towing. The bags can be inflated from 5 psi to 35 psi to adjust for load. You can get an on-board compressor if you want (an extra $150) to adjust the air pressure. I didn't get it, I just air them up to what I want in the garage.