I have a 02 WRX and I love the car, but its my daily driver. SO far I have a couple simple modifications. I took of the airbox and attached the panel airfilter to the top lid of the airbox, creating somewhat of a short ram. I have a MBC that I turn up to 17 psi while racing, butturn down to normal pressure or less while commuting. I upgraded the grounds to the car (because the original ones seemed kinda crappy). I plan on buying a Digital boost controller and am contemplating upgrading the "blow off valve"(which is reallya by-pass). My question is really if any of these things will greatly reduce my engine/turbo life expectancy. I have a 100,000 mile warranty and if anything goes wrong with my car, be sure that when I pull it into the dealer it will be stock. Also, do any of you have suggestions for non-permanent, do it yourself modifications, or add ons that I can perform to this car where it will remain reliable and if will void the warrant,w ill be easy to switch to stock. Thanks for your suggestions.

 

The only real thing that will reduce your cars life expectancy is poor maintence activites and poor driving habits (like mashing the car into the ground).
If you are really that worried about warranty then you shouldn't have put the MBC on.
If you are looking for better mods that will not be noticable to dealers then look into ECUtek tuning.
chris