LIMICAR Cylinder Head Stud with 12-Point Nuts 218-4701 for 1989-2005 Mazda Miata 2-Door 1.6L B6 1.8L BP

So the price is good but there are a few issues with this product.For starters, the nuts included are 12 point 1/2" nuts.That is right, not metric. Although, even the 1/2" isnt a perfect fit but it certainly is not a 13mm nor 12mm.The tolerances in manufacturing just are not very precise.Another example of this is the hex it has on one side, you'd think it was for installation right? Wrong, it is as good as useless. No idea what size they were attempting with the hex but a 4mm will slip, 3/16 is too big... Maybe it is a 4.5mm? Or an 11/64?! No idea as i do not have either of those sizes and i doubt anyone else does if they even make such a size (which they dont).So your only shot is to double lock the nuts to torque them in which there are no intructions for so i used the ARP instructions they provide online.But wait! There's more!The thread is not the same from the engine block side to the side you put the nuts to fasten the cylinder head with.No idea if the ARP ones are like this too but for my application, the top side where the nut goes is a M11x1.25!!Go ahead and try to find some M11x1.25 nuts so you can double lock them to fasten these studs in better. Even highly specialized, metric exclusive, hard-to-find-fastener carrying places will not have such a nut.You will find some taps and dies and maybe even a timesert and/or helicoil, but good luck on just going down to the hardware store to get a fist full.So with all that said, my confidence in these things are not very high at all. I still used them and I am generously giving them 3 stars due to the fact they are one of the only other head stud kits for my engine and were literally less than 1/3 the cost of the ARP set.If my motor breaks into 2 pieces in a month or so, i will update this review.*knock on wood*

They have extra strength. The price is right and it is a great head bolt upgrade for a engine you racing. Where you freshen up the engine frequently. If nothing else try a set if you raising the compression.

miata is running perfect again

Love this item!!! Great buy!!!

Garbage