Brand new to this forum, I know I have an 04 300M which is a bit different from the newer generation 300s. Just wondering what kind of performance mods I can do due to the 04 having the same engine as the 05-10 300s/Chargers.
While it is the same engine, it isn't the same engine. It's a 3.5L, same bore, stroke, power ratings, there are a lot of differences. In a way it's like comparing the 1st gen 3.5 with the 2nd. The 2nd gen and LX 3.5 are visually more similar at a glance but the layout of your motor actually has more in common with the 1st gen, or the 3.2L in my wife's Intrepid. Other than the alternator, everything else mounted to the front of your engine will swap directly with the first gen (power steering pump, AC compressor, serpentine and V belt tensioners) nothing mounted on the 05 will fit, I believe the actual block casting was revised since the oil filter is vertical and up front rather than hiding behind the power steering pump among other things, the alternator bolts straight into the block where your AC compressor is rather than having brackets making it much easier to change, AC compressor is about where the power steering pump is, and everything shares the serpentine belt rather than 2 belts. A couple of years ago my wife loaned her car to a friend for an out of state trip, the AC compressor seized, instead of calling me immediately (I would have told her cut the V belt and I will fix it when you come back) she and her bro in law took it upon themselves to try to fix it and it became a cluster fudge which had to be towed over 200 miles home. I used the AC compressor, V belt, serpentine belt, tensioner, from the 97 I had in my garage so it cost me nothing except some R134 to fix it. as for 04, 05 engine differences, I haven't even gotten into the heads, intake, starter.