has anyone ever heard of BillyBoat dpipes and exhaust

Yes. B&B is the OEM on APR exhaust and DPs. It's the same stuff.

what about the thermal exhaust how good are those

ding ding

you should hear those things on vettes and STi's holy moley they sound good :)

I don't believe Thermal makes an exhaust for B5S4s. A lot of people use them on the B6 though.

they use baffled mufflers which sucks on a turbo car . and the DPs are too small

which S4 exhausts do not use baffled mufflers?

Borla and a few others cant remember

That all depends on intended use.
 

For Stage III and beyond, I would concur. There are better options than the BB/APR equipment. However, on K03s, it's well behaved, excellent quality, and has good flow.