MSDS Headers

I am going to go look into purchasing a 79' 928 tomorrow... its a 5 speed and according to owner in great condition and i can probably pick it up for about $2500 which ain't bad. I was looking for aftermarket stuff for it since its got the 4.5L 219hp engine in it and came across MSDS Headers here (http://www.msdsinc.com/exhaust_1.htm) that claim to increase a 928's hp by 23%??? I have dealt with headers in the past but never have I encountered that much of a gain.. correct me if i'm wrong but wouldn't that bump the HP up to 270? I see that they are 500 bucks but if they can bring that much more of an improvement I will definately purchase these as well..... :naughty:

That HP increase is real, I saell a lot of those headers.