How much of a power difference would there be between a stock F22a6 Header and this header on a 94 F22B2 Accord

http://cgi.ebay.com/ebaymotors...QrdZ1

any input would be helpful

 

Any horsepower increases anticipated from a header installation would be minimal by itself. The real improvements are realized when you make improvements to the entire exhaust system. The reason?
You must visualize the entire exhaust system (from the cylinder head exhaust valve head to the muffler exhaust tip) as a single pipe of a finite size through which you're going to force (flow) as much exhaust as possible. The reality of it is the system will only flow as much as the most restrictive point will allow. IE: Improving exhaust flow thru the header will have no net effect if your mufflers' restrictive etc.
A well designed system could get you 10 to 15hp at the wheels (at specific rpm ranges)
Honda's appear to respond well to the 4/2/1 style header. There has been some speculation that the collector portion on some brands could stand to be enlarged.
If you're hot for a header, be ready for increased underhood noise and heat; and make provisions for them.

P