yellowjacket, if you are looking to get into the competition scene, then you can pretty much disregard what im about to type.
you have to look at it from the dollars to S-units ratio. as in, how much money/effort am i going to spend to gain a certain amount of S-units on my transmit signal.
remember that to gain 1 S-unit in someone's receiver, you have to quadruple your power output. if you havent heard that before, you may doubt it, but i assure you, its tried, true, proven and tested.
you can go here if you want to read more about why:
Adding a linear amplifier! How Much Will It Increase My Signal?
that being said, you have already gone from a 4 watt radio, to (im guessing here) about a 100-120 watt deadkey right?
(of course you should only be deadkeying about 1 watt into that amp, but more on that later)
going from a 4 watt deadkey (stock radio) to a 100 watt deadkey is about a 2.5 S-unit increase.
now, to get just one more S-unit out of that setup, you would have to run a 400 watt deadkey, which would mean swinging about 1600 watts at 100% modulation.
how much more money would it cost to get that extra S-unit?
if you are only talking about getting MAYBE 100-200 more watts out of that amp, you can see how this could be a big cash outlay for a barely noticeable increase.
right now you have a great setup with a 1x4 amp and a 150 amp alternator.
since that amp has a driver transistor, its very important to only deadkey 1 to 1.5 watts into that amp.
as for the swing, well thats up to you, but if it were my setup, i would be happy swinging up to about 10-12 watts PEP from that 1 watt deadkey.
that should give the amp all it can handle without killing it.
like i said, everyone has different goals and wallet sizes, so its up to you.
LC