Now that hijacking my thread is complete with cross-dressing. Let's get back to WHY I BROKE DOWN IN THE FIRST PLACE?
What would cause the exhaust valve not to seat properly therefore causing the intake valve to collide with it, breaking off. Then with the loose intake valve slamming into and taking out the spark plug electrode and then gouging the piston face?
Could it be bad fuel, manufactures defect, timing, heat or carbon build up?
I just don't want a repeat of this.
Another question, why the concern about how much I'm doing in engine mods? What's wrong with polish & ported heads, new heavy duty pistons and a new 58 mm throttle body? Along with the less costly mods some of you are recommending I do instead?
I'm not just interested in horse power & torque but longevity and integrity as well.
Keats already answered the first part of your questions and I'd have to agree with him.
In regards to the bold faced type in your questions.....for me anyway.....it's a two fold answer.
Keep in mind that the weak link of hte 110" is the thing that costs the most to repair, is the flywheels. Taking that into consideration coupled with trying to keep our motors covered by the warranty (and extended warranty down the road) we aren't willing to push the mod envelope to the point where there's no way they'll warranty the repairs (again, keeping in mind how much the lower end repairs are $$$$

$$$$) and it now comes out of your pocket.
Along with those considerations, for many of us it's not our first rodeo. For years I spent bucket loads of money for just a few more HP or a few more TQ numbers. I also learned (school of hard knocks, over and over) that when you start bumping compression generally that's when you start having the seeps, weeps and leaks as well as long term reliability goes down hill real fast.
All things considered for many of us that have run the hot rod gauntlet for years, we just want a well performing bike but comfort and reliabilty is now equally important.
This is all just my opinion and I don't speak for anybody else. However, it does come from experience as my wife's 09 Street Glide has had the motor replaced under warranty from the MoCo at 30,000 miles and my 10 Screamin Eagle Street Glide had a complete motor rebuild (flywheels on up) under warranty from the MoCo at less than 30,000 miles........both bikes the flywheels went south. And that was without any headwork!

It's just a huge roll of the dice that most of us are old enough and experienced to know the odds just aren't in our favor going beyond what has become the norm here.