I dunno. It all depends on the car - I find having engine mods and bodykits on most European cars horrible and, for some obscure reason...how do you say...sacreligious? It just doesn't really seem 'right' for European cars to have insane modifications done to it, but however, I do like some cars with some mods, such as the Kleeman CL55 and the Novitec 360. But in general, not a fan.
On the other hand, I feel that Japanese cars really suit modifications - maybe I'm just more used to it, but it just feels more 'right' on a Japanese car. For instance, a stock S15 looks, well, boring, but on the other hand, fit an S15 with a Vertex Ridge bodykit and you instantly have a desirable and more agressive looking car.
So it really depends on the car I guess. Some cars don't suit modifications, but some do.