Personally, I like "incognito" upgrades that do not harm the general character of the car.
Hood scoops? Not on a Chrysler. Dodge or Plymouth, maybe IF they are the correct ones. The reality about hood scoops, according to the old Direct Connection Race Manual, is that to be effective, they must have 30 square inches of opening for ANY benefit. So, you see where that's going. PLUS they can be flaky to "see over" to drive, to me.
The 15x7 Magnum 500s can look good, but a CHRYSLER needs whitewalls on it. BUT being it's a Newport, the 15x7 police wheels and hub caps can look good, too. The 15x6.5 mid-70s Charger SE Rallyes can be good, but with the 1970-style centers. NO need for 15x8s, for any reason. When I put 14x6.5 station wagon wheels on my '67 Newport 2dr, with P245/70R-14 BFG Advantage TA whitewalls (long time out of production, as when I bought them in 1981, they were getting ready to end production), I had to finesse the wheels past the rear brake drums just to get them installed. Clearances are that tight back there, due to the body contours.
2.5" dual exhausts with quieter mufflers will support any V-8 option you might desire. Stock-style rear pipe ends, too. Chase the Chrysler HP exh manifolds. Easier to deal with than headers, in many ways.
The reason the rear pipes drag, or are more prone to it than other brands, is that the C-bodies have longer overhangs on each end of the car. Notice that past the rear wheels, the body angles upward, too. Keep the ride height LEVEL. That way, the front suspension has enough travel to not be bottoming out on bumps and such. Plus enough space so things can be carried in the trunk and not bottom out. Opt for the "HD" rear springs. With the car level, the headlight night-time vision range is better, too!
Understand, too, that a "500 horsepower" engine might sound good to say you have, but that much MORE power than a stock 440HP only happens at 6000+rpm at WOT. Even with the stock 440/375, there is more than enough TORQUE to cook the rear tires.
You can NOT make any of the older cars match modern car performance, unless you want to spend lots of money for a ZF 8-speed automatic and the electronics to run it, for starters. There is a thread or two in here about just that. Except that now controllers are available to run the transmission, aftermarket, rather than re-programming a BMW controller or using a massive amount of external pressure sensors and such. Only really flaky deal might be the adapter to fit it to the back of the RB V-8.
With all of the torque multiplication that ZF low gear can provide, you'll also need some sort of traction bars hidden under there, too.
You CAN have as much fun driving around in a 4-dr sedan as you can in a slick 2-dr hardtop or convertible . . . as for driving it goes. Just resist all of the exterior things that say "I THINK I have a hot rod here" vibes. Do a slick crimson red metallic paint job on it and they'll notice it anyway, without having to "prove how much power is under the hood".
Take care,
CBODY67
