i have the eBay strut tower braces and subframe braces on my EF chasis and they helped tighten up the car thru the corners.
front and rear sway bars help with traction (with the rear being tuned in for your driving) and replacing your cross member with a traction bar can help stop wheel hop/loss of traction when launching
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if you can only race me in a straight line then whats the point 
...91 SMF SCCA
http://www.flickr.com/photos/8341770@N07/5601083432/http://www.flickr.com/photos/8341770@N07/5601083432/ by http://www.flickr.com/people/8341770@N07/, on Flickr
I see people out there spending money on the car to improve it … If you spend half that effort just working on your driving skills, making you and the car work together as a team, then you’ll go faster – period. To make the car go a second faster on the track takes a lot more energy and money than making yourself drive it one second faster.
– the late Tom Thrash SCCA Solo E Production