I did also use and would recommend Aviattic's resin extras for this kit, the cowling and the 'peach basket' pilot's seat. Pity that I haven't managed to produce a decent picture of the seat, but it is indeed there and is a nice feature of the model. In fact, I'd say it's such a characteristic feature of the type that it's almost an essential purchase.
I spent a lot of time on the interior, and now I wonder why, because I didn't appreciate how little is visible once you close it up. No SE5a-style 'skylight' to lighten it up. Probably my most futile act was to carefully place the murky instrument decals Roden provide, which end up far away in the interior, and as it transpires, were mostly absent from the original machine anyway.
Mark