There is some minor tuning that Larry has done to my car which may have made a small difference. The I/H/E may have improved that a bit, but the difference is very small. In fact, I haven't gotten around to doing the headers yet. It's more toward the car running better and cleaner than putting out more power.
That said, there are chips that may give you a noticeable improvement. They basically do some of that tuning for you. Personally, I do not like aftermarket chips and will not use one on my car. I was pleased that Larry felt the same way the first time I met him and we chatted. One of the things they do is advance timing at higher RPMS.
Before installing my NOS kit we made sure to check my NSX did not have an aftermarket chip for that reason.
Having the car dyno tuned by someone VERY good is the way I go when the time comes. I played with all kinds of chips back when I had a vette. Then I finally bit the bullet and had it dyno tuned personally by one of the best for that car. It cost me, but the difference was considerable. If I ever decide to tune the computer in a car from now on, it will be that way. Never a chip, ever again.
That's the only thing I can think of on tuning a stock or I/H/E NSX. Blown or otherwise is a different story. Chips are meant for the stock (or close) application and are 1 type fits all. They do things I don't like. Chips like the Hypertech (which I don't think exist for the NSX) allow you to tune yourself. Most people who use them end up slowing down their car instead of improving it because they think they are good. They're not. Neither am I. I let the pros do it.
INMHO, dyno tuning is the way to go if you really want to get that bit of extra performance out of a I/H/E setup, but it's not necessary. You could spend that $500-$1000 better elsewhere. Unless you have an automatic, then it may be worth it.