My point is they are not proper extractors. They shouldn't be sold as extractors. They are tubular replacement manifolds. Proper extractors have the correct primary pipe lengths to make sure that each exhaust pulse reaches the collector at different times, this is what causes the scavenging effect or "extraction" of the exhaust gases, hence why they are called "extractors".
Yes, they would be better than the factory cast manifolds, but not by much. The person who sold them was misleading if he called them "extractors".