I have used both and prefer the Heli Coil system as it is pretty straight forward. The Fix a Thred is top quality but is has some adjustments in the setting tool which are o.k. after you use it first time. The tap on both are very good quality, the Helicoil you need to have your own tap handle to use it, the Fix a Thred had a combo handle that will fit the tap. The inserts on the Helicoil insert tool is straight forward and the inserts have a tighter coil to thread into the tapped hole. The insert is also meant to be broken off with a tool and pried out, the Fix a Thred has an adjustable collar on the shaft that allows you to set the depth of the insert. The coils on the insert are more open and the theory is they turn and compress into the threads that you tapped. I can't argue that it is� a very tight fit. What I found was getting the first thread to catch was a bit tricky, too much pressure and it would skip out and too little and it would just spin. Once you get the feel of it catching and after 1/4 to 1/2 turn then you can put downward pressure on the tool and it will thread nicely. One thing though is I had too much space on the collar and the last thread stayed up and missed following the coil below it. It actually locked up the tool shaft and I like to have never got it out. I finally did with a pair of vise grips and took a flat screwdriver blade and knocked the coil down on top of the insert so no gap. It's only a one time mistake. They do not want you to pry off the insert on the coil but the installation tool is meant to break it off by a downward tap on the handle. I didn't want to do it as the pieces would have been in the water jacket. I am leaving it on as the Fix a Thred is deeper than the Helicoil insert so I will just let the head bolt push it down. I would use both systems and probably give it 55-45 on Helicoil
