Supersprint. In all my time owning and modifying cars, no company has come close to being as consistently excellent. Perfect better than factory fitment, great build quality, made in the western world, and properly researched.
All that said, the main reason I keep coming back is because they are
honest. Their dynos are true if not conservative, and in my experience they will never make up gains to get a sale. Case in point, I asked them about their 130i muffler, got a detailed response on weight and DB, and they clearly stated that it won't gain power.
Customer for life.
