98supra6sp

Has anyone out there on this forum attempted this modification. Are there any real proven Horsepower gains on this motor setup. I have read numerous BFI mods and of course they are all on earlier model Sc400's. My Rod Millen exhaust is due to arrive today and the front end of my car is completely disassembled for the complete re-spray and I thought now would be the best time to attempt this mod. Is it a lot louder than stock. This car as most of you guys know is for my father and I wanted it to sound a little more like a V8 for him but nothing too loud or obnoxious in HIS opinion. Has anyone attempted just a cone filter on the end of the tubing and than fabricating a closed air box of some sort. Any ideas or links to pictures of a 98-00 model with this mod would be greatly appreciated.
Thanks,
Mark