I agree with everything formula31 said. The Thunderbolt 4 does not have a rev limiter and is a darn good ignition system. I would make sure that you are jetted correctly because you are requiring more fuel than your stock 330 set up. Also, a fuel pressure guage is not a bad idea.

how do i know if i have a thunderbolt 4 ign?

What prop were you running before? From reading your post you have not done any changes that are going to yield a bunch more torque in which would be able to spin a bigger prop. Everything you have done is going to gain you more horsepower more so in the upper rpm's. You may try the same prop and see where she stops pulling at. Or check the dyno sheet if you have one. Remember, Torque tells you what you can move and horsepower tells you how fast you can move it. Thanks, Cam-shaft.

I am running the same prop 24 bravo 1, the same carb and intake the same ign. I do have more mid-range power you can feel it the motor is a lot quicker. Last year 330hp 3000rpm=40mph-3500rpm=45-42-4300rpm-WOT=55mph; this year 3000rpm=45mph-3500=50-4700rpmWOT=62; this is the same prop same gauges, When you are cruising say 3500 open it up it takes off like a rocket then falls on it face acts like I run out of air/gas.

Also, I have a mirage 23 prop for a spare I tried both props (bravo1-24) last year and the only difference in performance was mid-range speed had more cruising speed top end was the same. I just think it should more torque and rpm.

That does not make any sense. If you are spinning the same prop as last year, your speed will be the same as last year at any given RPM. Did you change anything in the carb to accomadate feeding the engine more fuel at the hight RPM?

That is exactly what I am thinking. the prop is spinning the same speed. Nothing has beed changed since last year only what I have said. It doesn't make any sense to me I think if you go from a 330 to a 420 you should see some more top end not run the same. From what I am seeing and been told, read etc there is a bunch of people exgerating and or lying or just misinformed.

Seems like your running out of fuel. The stock fuel system/plumbing will probably be ok for you (I had 450hp running stock fuel setup and had 6 -7lbs fuel press at 5200). Although, you should of stepped up the jets to accomodate your upgrades. I would run it and do some plug checks. run WOT, and get it shut off as quick as possible after comming off plane. pull a couple plugs. Also, get a fuel pressure guage mounted at the carb and check pressure at 3500, 4000, 4500, WOT.

you shouldnt speed up at the same rpm with the same prop. maybe your tach went bad.

Bajarunner....you need to rephrase the begining of that statement to......

It's IMPOSSIBLE to speed up........