RE: Welcome to Club SAITO !
A Turboheader is the way to go IMO. You could use a 90 degree from them and then the 45 extention from saito to get the Turboheader behind the engine and pointing down. Then the only cutting in the cowl would be in the bottom where it will be less noticed. You would be surrprised how close to the engine you can get it all. Then the hole for the Turboheader can double as extra cooling exit area.