ramman87 - My wife's Nitro has the 3.7 in it and it has some pep to it, scoots around town nicely but it is also about 1000lbs lighter than a rcsb ram. There is nothing wrong with that engine but it should never have been put into a heavy truck. Figure the engine is rated at 210hp at the crank stock, that is right around the 150-160 mark at the wheels. In a car, its not horrible, but in a truck it just doesn't cut it.
Just to get a better idea, to hit what a bone stock 3rd gen 5.7 hemi puts out, you will need to add at least another 100rwhp. By all means, if you want to try to build the engine up, and not just slap a supercharger or turbo onto it, then please do so. Just know that there are no superchargers or turbos specifically for the 3.7 because they kept blowing the engine. The piston ring lands were not strong enough to maintain the boost. So if you are wanting to build the engine up you literally need to rebuild the engine, then get the performance parts, then have a means of custom tuning it.
If it were me, I would add up the cost on what it would take to purchase everything and unless you can do it all yourself, figure out the costs to have a shop do some of the work, and the down time in which the truck will be down to add all the parts to it to figure out if it is something you are willing to invest in. Odds are it will be cheaper to either buy a new engine/trans combo and PCM/TCM or trading in your truck for one identical to it with a 5.7 instead of the 3.7.
Or better yet, if you just want to have a quick street truck while keeping the same truck, the same 3.7, shave off as much weight as possible and do what ever bolt-ons as you have available (which I believe is a tuner, exhaust and cai, maybe a custom ground cam if you can tune it). You wont get near the hp increase as a hemi or 4.7 for that matter, but shaving off as much weight as possible can offset that hp difference a little.