Maybe see if someone out there will rebuild and modify it for you all those most companies will ship. It's really inherent with the stock CT9 they do loose puff high end, couple that with a restrictive manifold (it's not restrictive in a poor design way it just does the job it was desgined for i.e not 1 bar) and it will always struggle top end.
With something like the stock CT9 you shouldn't really drive at high speeds for long long times, the turbos are very small and they generate a lot of heat over prolonged periods which is detremental to the turbo. You have a fair few mods already, next a manifold would be the missing peice of the puzzle ragardless of top end speed. A Hybrid can always come later or you can go TD04 but when pushing the limits of the CT9 you need to bin the OEM manifold right away. If you run a stock car then the stock manifold is totally fine but if you want the most from her then it's an essential key piece to release those ponies
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