Need some advice

Stay away from Khumo! Unless you plan on doing no serious dragging or street racing. They are alright in water and for everyday driving. I happen to have a full set of Khumos on my 2000 GT with 03 cobra rims that are 18 by 9.5 which i think is lots of rubber for a street car. Well i went to some local drag races and ended up burning out well into 3rd gear... It looks great to do that but come on i killed my time and then lost to a 79 comaro everyone called the "intemidator." I still managed to be nipping at his heels by .039 seconds in the 8th (which is all my town runs) "roll eyes".
So in conclusion i feel that you should stay away from Khumos all together, unless i just happen to have the crappiest Khumos made, but most of my friend have the same problem with racing with Khumos as i do. So i would say go with the BF Goodrich all the way if you plan on doing any racing.

2000 Mustang GT
BBK Full length headers
BBK shorty X-pipe no cats
Flowmaster cat back thunder series
BBK underdrive pullies
BBK cool air intake
BBK chrome valve covers
Hurst short throw
BBK 75mm throtle body
Ford racing Aluminum drive line
lowered 1.5 inches
18 inch 03 cobra rims
cobra R spoiler
Steeda 2inch hood
Steeda chin splinter
black car with blue flames airbrushed on

i got the kuhmos 712 and theyre purdy good for the 90 i paid for each tire. good in rain like was said but i have yet to drag race with em so.

don't get me wrong the kuhmos are very good and relieable, but when it comes to racing they fall short of what BF Goodwrench rubber can do for ya.
As far as other mods to your car. It is all wether you want people to see them, hear them, or only know that you've got them after they see your tail lights.

kumhos are good tires unless you race, i went from bridgestone potenza re750s to kumhos and the new kumhos gripped worse than the nearly bald potenzas. i havent had any experience with the BFGs but the potenzas have better wear rating (300 vs 340) and cost a little less, and they grip like crazy too.