The stock bellows connects the intercooler to the plenums and works well under stock boost. Increasing the boost with a pulley upgrade greatly increases the stress on the bellows. Just have your partner blip the throttle while you watch your stock bellows and you will see. Under spirited driving conditions, it is possible for the stock bellows to work loose causing a leak - creating havoc with the computer trying to maintain equilibrium.

Our 3-ply heavy duty Silicone Bellows upgrade kit replaces the stock bellows with a much more rigid and durable bellows eliminating the chance of the stock bellows working loose. Works with the stock clamps.

This upgrade is strongly recommended for our Intercooler upgrade kit (NME5005).