Check the length of your serpentine belt if it's not new. Stock is 114.5 inches. When I replaced mine it had stretched to 117 inches. After replacement it made a huge "seat of the pants" difference. Cheap - easy. The dyno I did which had all of your mods showed 340 wheel hp, so you're right there. I added the Needswings crossover ported manifolds since the last dyno test so I don't know what they might have added (if anything?). I note that there is no info on dyno testing for these crossover manifolds on Needswing's site. Wish there was.

You are probably at the point where you will need to ensure good fuel flow - at least that's what has happened to my SRT. Opening up exhaust flow at this point might just make A/F ratio worse - adding air, but not fuel. I added an SL55 fuel pump to make sure the engine was getting all it could with the standard injectors. Once done, my A/Fuel ratio normalized. Once you get to where you are HP wise, it's likely that the best mod you could add is a Limited Slip Differential. Horsepower that can't be delivered to the pavement is worse than useless. It made a HUGE beneficial difference in my car. Expensive, but zero regrets.