STOCK ratings = 330 ( SRT6) - 215 (NA) = 115 HP difference.
The SRT6 can approach, or slightly exceed 400 hp correctly modded.
The NA, with the additions I listed above will have somewhere in the neighborhood of 250-260 hp.
Add NOS ( at you own risk ) and you MIGHT see 280-290, still over 100 hp short of a tricked out SRT6.
If you really want to keep the NA/Limited/Base body, look into doing a V8 swap.
Then, you'll have some serious power.
NOTE: most V8 swaps have been done with an automatic 5 speed, but I do know of at least one that was done with a 6 speed.
Problem is that the MB 6 speed manual is not really rated to handle the HP that a V8 delivers.