A number of people have reported problems with the Holley pumps.
The generally accepted best manual pump you can get is from RobbMc, they have 550HP and 1100HP versions. I suspect in reality you'd be oaky with the 550HP version, unless you really intend to spend a lot of time at WOT.
Find them here;
http://www.robbmcperformance.com/products.html
Julian
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