HP is bragging rights. Torque is what makes these cars so much fun to drive.
With my 427R I added 3" stainless specialties mufflers. Lots of dyno tweaking gained me 7 hp at the top end. They are loud and sound bad asss though. Then I added the big port headers that wouldn't restrict the flow. Lots of dyno tweaking gained me no horsepower and lost @ 30lb ft torque down low. Also cost me .3 seconds on my ET at the dragstrip. A "respected dealer" (maybe the same one referred to above
) told me this is exactly what would happen.
I am always amazed a the threads claiming the big performance gains from exhaust mods. Sure didn't do much for me. Some guys are just lucky I guess?
On the other hand, these cars are all about the fun, plain and simple. If shiny loud mufflers make you feel like you're going faster, then they are worth every penny. No arguing that point!
Enjoy.