hi and wlcome shadowmaker,
personally i would recomend the handling side , certainly a good set of tyres and wheels, and a good set of shockies should certainly help the handling.
and have a look around to see if theres an upgrade for teh brake, which tends to be a bit soft at the best of times !!
and lastly a look here
http://www.rbinnovations.com/catalog/index.php
, and adapting one of those chargers to suit ,
which has been done to a tsn4 before
Adz..