What are we doing here, this for your car? I see you have a GT, do you have the top swap already done?
You need to see if the IC you have is made for a GenIII or a GenV. If its a gen III, yes it will bolt up, but the core will not be where it should be for the outlet of the GenV to "blow through it" is what were getting at.
GenIII stuff has to be made for GenIII stuff and GenV stuff has to be made for GenV stuff. You can mix and match, but you have to know the basic facts.
Read thread here:
ClubGP Message Forum troubleshooting
And see if that helps answer your questions you have.
~F~