I've been curious lately as to just how much top end power your missing out on when running the 1.10 vs the 1.25 housing on an S400 in a twins set up. I understand the reasons not to(drive pressures etc), but have still been curious. Please no more bias arguements, I just want to know what kind of HP is lost with the smaller housing?

 

I almost forgot to mention, its a HE351 secondary.