But I know for a fact that my dealer won't do aftermarket anything beyond mounting an exhaust... They told me it was because of their generous warranties including labour and if the labour is related to a non-nissan part going sour then it gets messy with whether or not the troubles are due to the install work (Nissan happy to give free labour) or due to the part itself (Nissan not happy).
However this could likely be overlooked if the service dept. is hungry as suggested below...