i had my stock 5.4 with a suopercharger dyno today, we ran in to a problem with the stock exhaust, (when i say stock i mean there's no cat's onlyn a flow master) at about 4500 rpm it stoped flowing and building more top pressure, but my horsepower was 327 with 399 torque with only 7 pounds of boost, he said i needed to change out my stock exhaust and i should see abot 30 to 40 more horsepower, what you guys think, and what size tubes should the headers have for my truck, it's not a 4 wheel drive

 

2.5" dual exhaust all the way through.

 

which is better short or long tube headers ? and what's a good name brand header ? what should be a good muffler also for my truck, i want something that has a good deep sound but not too loud ? thanks i have a few pictures but i dont know how to post them any help would be great, thanks again

 

Long tube headers and a magnaflow. 2.5" with mandrel bends and throw an x-pipe in there.

 

For what its worth the stock manifolds flow pretty well. Mine flowed fine at 400rwhp and Fatherford pushed his to 450. That Flowmaster is killing you.

 

327 399 sounds about right

 

Some Dynos read high and some read low.

My SC blew 11psi through a completely stock Ford system without a problem (Only problem was blowing the exhaust collector off)

What kinda Dyno was used?

 

agreed those flowmasters are robbing you 30-40hp

 

I dunno I run an single in dual out Saleen (Edlebrock chambered) muffler and my numbers are the same as everyone elses around 9.5 PSI

 

Already posted on this thread ha ha.

 

If your running a standard cab you can get a OBX Lightning full system (headers to tips). However I was pushing 14psi on a factory lightning exhaust with all 4 cats intact. When I went to 2 high flow cats and long tube headers I lost tq on the low end. IMHO I don't see you needing headers, but if you do get them go with long tubes. The most I see you needing is 2.5" true duals with a dual in dual out or 2 single in and out mufflers.