Lemon Drop,
there was a modification to the Trent 800 inlet cowls to reduce the 'buzz-saw' noise on take-off, which was deafening biz class pax in row 15+16, as it exceeded basic H&S noise levels. I think the cost of replacing the inner barrel panels was around US$140k per a/c. Plus the panels were heavier, so we are still paying for them in fuel costs....
But of course, we do it because we love our customers and want to make them as comfortable as possible - fawn, fawn, fawn.
So still believe the earplugs are cheaper for the GE90 moo-cow.
Best Regards,
N1 Vibes