With those engine calibration changes, better upgrade the brakes and suspension to handle that power, TOO!
Be sure to use the reinforced header gaskets to decrease the probability of future header gasket leaks. Might even consider the special header bolts to keep them from getting loose?
The TTI headers might be expensive, but they have been the go-to Chrysler Corp C-body headers for a very long time. Only thing is the under-car systems are not specifically for each different wheelbase, so some alterations might be needed.
It IS also possible to have great flow and it not be noisy. '72 Imperial mufflers have the larger pipe inlets and outlets, with basically Street HEMI muffler flow and a bit quieter sound. Certainly NOT that raspy (think 5.0L Fox-body Mustang) sound! Plus, they are correctly sized for C-body cars! Getting larger diameter pipes over the rear axle is tricky, which is where TTI's expertise can come in handy.
The 1969 Polara/Monaco 440HP cars came with the Chrysler Corp Street HEMI mufflers under then from the factory. Had enough flow to let those cars make enough power to run 150mph in the certified Michigan State Police Car Tests. That ought to be enough exhaust flow for your application, no doubt. That speed record stood until the later Camaro TPI police packages of the 1990s, with the Camaros only going about 2mph higher.
PLEASE understand that to many in here, a "New Yorker" was the nicest, most luxurious car Chrysler Corp built, other than the "better" Imperial. Not something to build a "loud hot rod" out of, but for great comfort and great highway handling with very substantial engine power that would easily last 100K miles with very little problems. 300s were the "performance Chrysler", by comparison. Although, many New Yorkers were "trashed" in order to put their factory 440s into B-body cars, in earlier times. Or in the case of the earlier 1960s, to use for parts to restore the massively-more valuable 300 Letter cars of back then. So, to some, putting a loud engine, with a 2800rpm stall speed converter TF, with a loud exhaust into a New Yorker is "out of character" with the initial intent of that model from Chrysler, being more suited to a Plymouth Fury or Dodge Polara, or even Chrysler Newport, by comparison.
Enjoy spending your money!
CBODY67
