Yep, finally a thread with some good common sense regarding modding. For those asking, yes a dealer may try to invalidate a warranty for "anything you do" and these dealers sometimes need to be shown that excerpt in the book or the magnusson act, which states they may not deny a warranty for a problem unrelated to the modification.
Then it becomes being smart about the modifications and not doing stupid stuff. Slamming cars with drop springs works ok some of the time, but it also causes struts to bust through the frame some of the time. A mild drop probably won't do it, but you are putting yourself more at risk with a modification. There are subtleties. Drop springs basically have to support the same weight with less travel, they have a higher spring rate for this, but not all of our car configurations weigh the same, AWD vs RWD, 2.0, 2.5 and 3.3. These all weigh different amounts. Are the drop-spring part numbers the same for each of these configs? If so, it means some of them will end up significantly less than ideal. When I got springs for my BMW, I had to special-order some from ACS Europe, because they were the only ones making them specifically for my Grand Coupe configuration at the time. There were multiple other springs available, but they were not matched to the actual weight of the vehicle, in other words they were a "one size fits all" for the entire rim and configuration range. Then there's the damping issue. I was able to increase the damping by getting a computer damping update for the electronic shocks. Although the commuter upgrade was Dinan and the springs ACS, it matched nicely. A lot better than running around without increasing the damping on drop springs. For some of this stuff, people do it only for cosmetics, which kind of limits the usefulness of the car as far as performance. You gotta know the impacts of what you are doing and what it might limit you to in the future.
Good point above about the exhaust. It's important to note that once you change the power output or delivery, you make it fair game for them to deny the warranty on anything in the engine or drivetrain downstream. This is where it gets tricky, because you may have honestly just had a flawed part that should not have failed, modification or not, but now if the dealer is going strictly by the book, it won't be covered. You'll hopefully find some good common sense approaches out there and there are good dealers in this respect, but again, you open yourself up. You need to do your homework with a mod and make sure you are getting all of the required additional
mods to support what you want to do (if it requires additional). Like when I went stage 1 with my WRX, then stage 2, where I stopped. At stage 2 there were several parts required to run the higher tune, from the turbo-back exhaust, intake, bigger intercooler and some other bits. Going to a bigger turbo would require even more, better fuel pump, bigger injectors, possibly forged internals, etc. And then you are putting that stress on the drivetrain, so expect to replace the clutch or possibly trans issues, or swap the trans before something bad actually happens...Basically, this increases exponentially as your level of modding increases. People can and still do mod at those levels, but they dump a lot of money into the car usually when they are doing it right.
Also important to realize how the dealer works in this situation, they get reimbursed for labor and parts from the corp, so if the corp decides to say they ain't paying for mod-related warranty stuff, the dealer isn't going to be doing that stuff for free or out of the goodness of their heart.
