Have you done before and after RR tests yet?
As you maybe beginning to understand with these threads, the majority of people are not driven by quality, they want value for money. If this wasn't the case, we'd be driving BMWs, not Renaults!
Likewise, most people on here like loud exhausts. Is there no way you could do a quiet and loud version?
I am in full support of what you are doing, BTB are great and i fully understand workmanship costs. I am concerned you didn't actually do enough research in the first place to make the project a success though.
Personally i would of gone for a V6 as the first car. You can't not make a V6 sound good, which will give a good impression to 2.0 owners. Naturally owners of Vees will be more affluent and be prepared to pay for the best too.