Here's the blog post from way back when, where they did a bunch of variations on the same dyno on the same day. Also, the sidenote I like to point out - virtually no increase from removing the CATs.
They saw a 14HP bump with just the OFT E85 tune on an otherwise stock FRS.
I use the OFT myself - I just put the tune on in the summer and go back to 93 for the winter (because E85 is very hard starting in the cold - even the fifties). You can usually find someone selling their old OFT for $300-$400; just make sure it's been unpaired from their car. The downside is you have to manually swap back and forth vs the true flex fuel scenario, so if you take road trips, bring the OFT with you in case you need to swap back.