I told myself it was soft ,before I build the duster I daily drove a 2008 Saturn 2.4 engine an it ms definitely more quickerYou know, I see you just itching to spend money with no real idea why your combo is soft.
You need to figure a few things out first.
number one is to check out your engine;
do a compression test.
While the plugs are out, look at them!
then check the power-timing.
then make sure that when you floor the gas pedal, that the 4bbl actually opens all the way and that the choke is not stuck on, that your exhaust is open, and that your engine is coming up to a decent working temperature.
One dead cylinder is 12.5% soft.
All 8 cylinders at 10% leakdown is almost the same as one dead cylinder.
Maybe you have a burned valve, or a bad cam, or just crappy cam timing. or a plugged exhaust.
These are the basics
Number two is the trans
do a stall tested and an efficiency test.
Number three is the rear end;
figure out exactly what ratio is in there
Number four is the chassis.
Make sure the brakes are not dragging, that the U-joints are ok, empty your trunk, leave your porky friends at home, and air up the tires.
number five is inlet air
What elevation are you at?
What size is your Magnum, for sure?
How is she getting air?
and is she getting enough air?
The hardest part to making power is getting the air in.
And finally;
Who told you your combo was soft?
That's a trick question.
If you told yourself it was soft, then soft compared to what?
If somebody else told you it was soft, do you trust his judgement?
All this is very good Information ,I'm at work an then I going to school right after so after I'll try to respond, I drive to work an school no highway driving done yet ..the fastest speed limit is 55 mphwhat kind of driving do you like to do? run on the freeway and keep up with traffic? run hard from 0-60? get an idea of what you want your cruise speed RPM with a calculator like this: https://www.tremec.com/calculadora.php
keep in mind, this will estimate cruise RPM probably 100-150RPM low, because this calculator does not take converter slip into play. try figure out your current ratio as well, to determine what ratio you may want to go to.
IF you decide to replace the rear, you can probably sell your current one for a decent amount, I'd be interested if it was in indiana, michigan, or ohio....don't know what the A body parts situation is down there, but up here, you can't find much. your best bet for upgrading the rear is to look towards a ford 8.8 out of a ranger or explorer, especially if you want to move to a 3.55-3.73 ratio, disc brakes, etc....a lot of them are sitting in the junkyards with limited slips, too. an A body 8.25" is about 57" or so drum face to drum face. a ranger rear is 58.5" mount face to mount face, an explorer is 59.625". the ford axles have the pumpkin offset, if you shorten one side to center it and use the same side axle shaft on both sides, it ends up being 56.625".
XJ 8.25's are an option, too. autos are mainly 3.55's, manuals 3.07, might find a tow package with a 3.73, might find with a limited slip....only problem is they're 60"-60.5" drum face to drum face, which means you'll need to use high offset (like +30-45mm later model mustang) wheels to not have the wheels hang outboard of the fenders.