As for "modding" a car - you do realise that every Rand you spend on a modification results in a considerable loss when it comes to trade in.
I squirm every time someone brings in his modded Subaru, and starts telling the Used Car evaluator what he has done to it - each time he opens his mouth, the car loses another 10K........
Why is that the case for cars but not for bikes?
On the bike market it's always a bigger selling point if it has aftermarket pipes fitted, air filter and maybe a Power Commander. Obviously not proper engine modifications as that leaves a whole lot of question marks.
And in fact if you crash your bike, often the insurance will even pay for the mods because the aftermarket stuff is often much cheaper than the OEM stuff. Guess this doesn't really apply to cars as it's rather hard to cock up the exhaust in a crash.
As for me, don't remember ever doing anything with a car but bikes...
2004 Suzuki GSX-R600
Yoshimura Exhaust
Zero Gravity Windscreen
Don't recall anything else, unless you want to count switching to fully synthetic oil.
2007 Buell Lightning XB9SX
Jardine Exhaust (blew up spectacularly)
Spec Ops Custom made Exhaust (cut and rewelded from stock pipe)
K&N Race Filter
ECU Remapped with Buell Race ECU
Brake Pads Upgraded (was going to change the disc when it ran out but that was warranty claimed so never happened)
Rear Sprocket (More for bling not gearing)
Can't remember but I think some other stuff.
2014 Triumph Street Triple R
Nothing just yet but it will probably get one of these by the end of the year.
http://www.twobros.com/sku/005-3980405-S1
In the case of bikes it's all about the noise for me and not really about gaining more power. Weight advantage is a bonus.