every engine can benefit from a good set of long tube headers!! shortys are half ***'d and ant much better than a good set of cast iron manifolds! dougs seem to be best fitting and best cost, orilleys has a sale on them every so often, headers and good exhaust should be first upgrade after any and all safety issues are fixed first!
Yup, my G8 had long tubes on it when I bought it and apparently just the headers and a full exhaust on that car are good for 40 whp before a tune. They can make a huge difference.