Correct me if I'm wrong.

When choosing headers for FI, the headers should have the shortest tube length possible, and Tri-Y is not needed.

The Dinan headers were designed to be the "icing" on the supercharger "cake". A major advantage of minimum length primary tubes is less heat soak underhood (running FI increases underhood temps, the added surface area of equal length primaries adds even MORE heat underhood).

Equal length Tri-Ys are best suited to non-FI engines.

Those who have tried to "chase" a few extra HP by optimizing exhaust pulse/merge/flow with FI, have found little gain after significant effort/cost. A simple pulley change will give you all the HP you could ever want, enough to grenade the motor.

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'03 X5 4.4 Sport, last of the M62s (8-03 build date)
I believe in deadication to craftmanship in a world of mediocrity!