I agree , 1 to 1.5 watts in on that little 100 should be like turning your radio into a dual transistored one. As far as hearing goes ? that would be your antenna system for the most part.
Try not to skimp on that area of your system. You might conceder having a reputable radio guy in your area tune your radio to the little box if you really don't have the know how yourself ?
If your 29 is stock ? chances are the 4 watts might be a little hard on the box ? , those little dudes will get hot in hurry ! Sounds like your on your way.

I see it's your first post , so let us know how it works out for you. Good luck.