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Well that problem was there in the first full tune when I swapped to PowerFC from Nistune, I asked them to fix it this time, it was only a touch-up tune and 'massaging' it in this time after the exhaust fix, nothing major. Its definitely a 3-4sec major power drop with downshifting, sounds tune related aye?

Well it's a result of the ecu doing something dumb, which it determines by how it is tuned. So yes, it is tune related.

I would be cranking some more preload on the actuator. They wouldn't do it while tuning due to the heat around the manifold and turbo scaring them away, but letting it cool on the dyno to try it out would have been cheaper than another tune.

Do you have a boost controller?

If not, what spring do you have in the wastegate?

Only other thing could be the smaller turbine housing (maybe it needs a .8?), but I dont know alot about the precision turbos so I'm not even sure what size the turbo is lol. Anyway if no boost controller then that might improve it, if it alread has a boost controller then it might need some adjusting due to the change in exhaust flow

Boost drop is easily answered. Reduced back pressure in total means less restriction all the way back to the inlet and less boost required for a given amount of flow. Choke off the exhaust again and the back pressure will report back to the intake side at high revs again and Bob's your older male relative....less boost drop off at high flow.

Oh that explains it then..4psi drop is a bit much though.. Yes I have a turbosmart T controller off gate and other end connected to nipple in compressor housing, 18psi spring in wastegate so not lacking in that department. One nipple on the top of the gate is unconnected though?

Cheers-mite be my next mod- will any ebay electronic boost controller like cheap china hdi do or only apexi avcr/ greedy profec spec 2 etc? Hope touch up tune wont be required as its already tuned to 22psi- Im about sick of all this tuning which isnt leading anywhere much.. :(

Yeah better way to do it, holding boost on top and bottom then bleeding the top pressure off. Id say the boost control is the issue with the boost tapering off up top but still doesnt explain the hesitation when downshifting

How's your intake ? 3 inch all the way and free flowing as Tao from hypergear has tested at 250kw there is a difference of 13kw going from 2.5 inch intake to 3inch

Also .63 rear housing may becoming at restriction on a 6cylinder and that power level and boost

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