most cars running big gt30s etc dont last that long anyway so i dont imagine it would matter to them, im talking 100,000miles lifespan.
i think they do aid lifespan but i haven't personally got any solid proof, only that a good friend of mine has an rx7 with almost the same spec that flutters away, mine had a HKS BOV fitted in japan. at 70,000KM his twin turbos were absolutely shagged. myns only at 62,000KM but they are not even slightly worn when i rebuilt it. both cars run turbo timers aswel.