I think they should put baffled sumps on all cars. I don't exceed speed limits too often. Like to do my 30s, 40s and 50s but I love to punt it around most corners that I come to. Kids have been sick a few times in the back, well only Abigail, Aimee shouts faster.
Bill has a video of the testing of rev limit in his forum section. Valve float occurs at 7500 rpm. Is yours a different setup in terms of spring stiffness?
Sequential twin turbo setup would be nice in a 500 bhp setup to avoid a lack of perceived oomph in the
lower rev range. I seen it done on a sierra cosworth but I take it your engine bay would be a bit cramped for that.
The mate dropped a tuned alh engine into a mk2 golf and put twin turbo compound set up into it but it definately didn't look standard. I'm not a big fan of compound setup anyway, much prefer sequential or parallel.