Hey guys...I was just wondering what might cause my engine not to rev like it used to. After I rebuilt my engine and got it all balanced it'd go 7600 rpm no problem. About 2 years ago a piston cracked and I threw in a replacement set without rebalancing and the redline dropped to ~7200 rpm... Slowly it seems to be getting less and less, although it pulls stronger than it ever used to thanks to twin 40 Dellorto's, aluminum flywheel, and MSD ignition. Anyway it's dropped slowly over the last year...7000, 6900, 6800, 6700, etc.... Right now it's having problems going past 6500 rpm. I think the stock single valve springs may be the culprit so I just bought some NISMO inner(dual) ones to help out...sound like a good idea??? I think maybe I should also replace the outers with some new ones too, but I figured the inner ones would help out enough. Does it sound like a valve float issue? The car pulls sooo good and then it just pretty much stops. Will adding stiffer springs hurt a 100,000 mile engine and cause too much stress/wear? Thinking about just rebuilding the whole thing, but I don't have a lot of time to do it right...basically 3-4 weeks to have it done and ready to be shipped to Japan. I'm thinking I may just buy a cheap A15 short block from a junkyard and start rebuilding it on the side...if I finish before leaving and the current A15 holds up I think this would be the way to go. Still pondering though....low compression/turbo/EFI or moderate compression/NA. Any thoughts/suggestions? Thanks!

-Andy