Radial and branch MVHR hybrid?

[Seeoda]

Hi,
I have a scheme house, over three floors. It is a tall but narrow house with its own branch MVHR system. Living in it has made be realise I deeply appreciate MVHRV, but the problem I have is that on the ground floor in the kitchen, the flow is too weak. There are a lot of food smells. The tested values are often just 2 to 5 (l/s) on this floor. I'd love a filter on the extract, but that would lower the pressure more. The kitchen has one extract. No input. While the system tends the system tends to be too noisy on the upper floors. I have flat channel ducts on the ground floor and the middle floor and round ducts on the top floor. The unit is in the attic on a hanging mount. It is a Vent-Axia sentinel. I don't have the budget to gut the house and change everything, so there is only a limited scope. I was thinking of some kind of hybrid system. Possibly a manifold on the ground floor to enable a second kitchen extract and maybe a second one to living room. Possible re do the flat channels to have less bends and better flow. With another manifold on the top floor to ensure a lower flow to nnoise sensative areas. Can you use manifolds on branch systems? I may be able to squeeze a radial duct or two from the attic to some rooms. Is this plan viable? 

Edited May 17, 2023 by Seeoda