ETX One-Piece Tuned-Port exhaust manifolds?

[DrewT]

I have seen some ads where Indmar is saying their engines have 5% more horse power and torque on the 2005 boats because of the change to the ETX exhausts.
Can these be put on the pre-2005 boats and will the older engines have the performance gains that the new ones do?

[Brian Raymond]

The ETX manifolds are an awesome application to our line of motors, it is a major improvement to our line of engine options. Here it comes. However, the improvement is major enough, that Indmar requires a engine # to replace these manifolds. If your motor was not equipped with these, they will not sell them to you. The reason being, there is a calibration change that must be made in the ECM(the motors brain box). This program is speically designed for the 340hp. intake manifold only to work with the ETX exhaust manifolds. Brian Raymond

[DrewT]

Thanks for the reply Brian. How about the Billy Boat exhausts that just came out? Have you heard anyting about these? If the exhausts are the restrictioin area of air flow on these engines, I wouldnt think that the engine management system would have to be reprogramed, but maybe I am missing something.