Steve,

Number of RSS items is controlled by the publisher of the pheed.

Some, such as the pheeds.com search allow you to contol the number of items used:
http://www.pheeds.com/bib/search.cgi?keywords=jimi+hendrix&format=rss&pre=5&suf=125&id=&template=advanced&results=30

You can change "results=30" to any other number, within reason. If you set it to 100 and theirs only 2 results, you'll only get two results.

However, each RSS pheed is different and not all allow have this option, although all Bomb scripts that generate RSS have this attrbute.

Also, The Newz Tuel only shows 3 items from each pheed on the "main" category page. To view all times, for each pheed click the link: