Training Change - Need advice!!!!

Ironman Louisville 2013 prep is coming along nicely.  I've spent the last 2 weeks stepping back and truly focusing on "base" training in my aerobic zone.  This has been a major adjustment for me.  After being told countless times by Jay that my base training should be long and slow I finally decided to listen.  Seems as though most of my running was on the grey zone.  Even though I was seeing improvement I wasn't working my aerobic engine and teaching my body to burn fat as fuel.

Given that I had a good season last year and was seeing improvement this year I feel a little silly changing anything at this point, but I believe it's best for me long term.  They say for burnout, over training and recovery this is how you should do it.  And given my history of injury and Asthma it made sense to me.

The biggest challenge with this new focus is that my training pace is VERY slow compared to what I had been running.  It's embarrassing for one, but scares me that ill also race slower because of it.  Last thing I want to do is change something that makes me slower.  The goal is to get faster at the lower heart rate, I'm just not sure how long that should take.

If anyone has any good experience with this please let me know!!!!  TriFest is this weekend and I'm racing the Olympic distance.  Hoping to see some improvement from last year.  Should be fun!  I'll post an update after that race.