Engine/Trany Mods - Curious

[bgsquad]

Guys, I'm always reading about your mods, and having a stock X, i started to feel the mod bug getting close but here we don't have much specialized places for good mods, so i am afraid of messing it up...

anyway, that's not the issue... what I was wondering about lately, is the mods some of you do on their engine and trany (dinnan and the like...) so I always wondered how would those mods impact the overall reliability and durability of the vehicle.

I mean the BMW engineers are not dumb, and if they designed the power plant and trany in this way, it should have been for a reason. so when you come and reprogram the trany and engine to hold higher RPM, burn differently, and squeeze more HP, wouldn't you be paying for it on other levels? if the system can handle more power, it would have been done in the factory, cause u know how the makers compete with their cars specs, so BMW would have extracted those extra HPs and improved the performance of their cars...

any feedback would be enlightening