I went to SEMA's website and from what I gathered that it is up to SOA to decide about your warranty not the dealer. I wouldn't trust that, even if the dealer says it leaves the warranty safe. If SOA caught wind of that, and you had a engine or tranny failure they could link to a engine mod, and goodbye claim.
Also the subaru dealer I am currently dealing with WILL not install any parts that are not subaru parts. Well except the sti parts, they don't install those either.