Solid like like 125psi; or solid like 185? Those are two completely different engines, but hey, they're both"solid" whatever solid is.
With 3.91s and Dart wheel-wells, you should already be past the limits of your tires to cope with whatever power your current engine is making, and serious acceleration cannot begin until that stops, which might not be until after 40mph with street tires, a 4bbl ,and a free-flowing exhaust. , 350 hp will only make for more low-speed tire-spinning.
If that is what you want then as RRR sometimes says "I'd" go with the Magnum which was born with a higher compression ratio already,(which really livens up the bottom end); and it has better than stock LA heads, (which livens up the midrange and top-end.)
Your manual-trans combo, really likes compression, at below 3000rpm. And with 3.91s, there is no
substitute for compression from 3500 to 4500 except cubic inches. Skinny street tires are you limitation. 255s are gonna be roller skates, in at least the first two gears.
350hp is easy to get and cheaper with a Magnum, without the loss of bottom-end, cuz it already has decent compression.
Do you need the compression? ...........No.
But I guarantee that if you drove two identical combos, one at 135psi and the other at 185psi, you will never go back to the lower pressure.
The higher numbers mean that you could give up those 3.91s. I drive mine with 3.55s but only because it revs my engine out in Second gear just before or at the legal speed limit; I hate speeding tickets. I can live with tickets for excessive spinning of tires, lol. It was just fine with 3.23s
