What is the cost range for header pipe or exhaust manifold repairs? on 2004 Infiniti Q45

What are typical repairs for this vehicle and are the repairs above among them? I am asking because a muffler repair shop stated the car has a leak further up toward the engine and referred me to a engine specialist. I need an estimate for potential repair costs. Thanks

Asked by for the 2004 Infiniti Q45
there are shops that specialize in exhaust systems. most engines come with a stock manifold. replacing with stock manifold the most cost effective method of replacement. $300.00 for the parts set(high end)+ 4 hrs labour(depending on difficult removal of old manifold is, it always varies). shop rate different depends on the shop.
replacing stock manifold with headers cost more. $450.00 for parts set. shop time should be relatively the same. headers will give vehicle different sound and a slight power gain.
if money is an issue, shop may have alternative method to repair existing part.
try different muffler shop. puzzled as to why the one you went to couldn't handle the job.