Header install is a huge PITA.......dont bother unless its longtubes. I dont care if the guy gives them to you for free. Read some of the install threads and you'll understand.

 

Long tubes or nothing. End of thread.

 

I debated over this same situation...my 'stang wears a pair of FRPP ceramic shorties. Just the reduction of weight, while still nominal, between a pair of cast iron manifolds and tubular headers will result in a performance gain....we take the spare tire out at the dragstrip...don't we???
In every modification I do, I try to reduce the weight of the vehicle. I consider it free horsepower.

 

I have BBK shorties and off road H. Made a nice difference and yes install is a total pain. If I had the chance to do it all again LTs would be my choice. Heck if you are going to pull everything apart go ahead and put the LTs in. Don't be cheap when it comes to exhaust. Think of the pounding that system has to endure. Ask me how I know. Boogie