well I just changed the gas struts on the roof(hood) and I'm not quite sure if I did the right thing. Yes, the ones on the B, were pooched, long past their lifespan, they actually worked against raising it, but the ones I replaced them with,Mazda R8 rear hatch struts are three mill shorter and the hood is definitely not operating like it's normal self.

My gas struts came from SGS engineering and they were listed for the B. They were, in actual fact, a couple of mil short but I unscrewed the ball socket from the rod and put a washer on the rod and refitted the ball socket.
My old struts had absolutely no pressure in whatsoever! Lifting the hood is easier but not that brilliant.

Hi, I also replaced my boot lid and hood struts using SGS struts. Fitted straight out the box no problems. Over a year now and good.
SteveD

Hi Dave. When you say you unscrewed the ball socket on the strut were you satisfied that there was enough thread left to trust it? These are stock Mazda struts made in Germany(Stabilus), so I don't know if I can do that, and they weren't cheap. I don't want to damage them. Also like you I wasn't overly impressed with the results.It's better but not much. And wouldn't you know it, the minute I buy them I see the proper ones on ebay advertised for the Barchetta.

Initially I was concerned but it took less washers than expected. I thought I would need 3 washers but it only took 2 thin ones to do the job. There was 7 to 8mm of thread and the struts push rather than pull. Also the ball ends weren't screwed on that tightly.
I also changed the boot strut (it was cheap enough) but there was no difference between the old and new one. Does anyone know why the hood struts fail? Is it due to their size?

On our 2005 'B' I fitted:

SGS Engineering GSC1280 regassed from 250N to 310N

These turned out to be:

NitroLift GS8-18-80-120 at 310N / 310N 04/15 193749

Perfect fit, no adjustments required.

For our replacement Mohair hood the extra lift means that the hood assembly in the down position is just beginning to lift so if you don't use the retaining straps then you have ensure it is well pushed down to begin with and then drop the hood lid cover from a slightly higher height to get it to latch down correctly.

On our 2005 'B' I fitted:

SGS Engineering GSC1280 regassed from 250N to 310N

These turned out to be:

NitroLift GS8-18-80-120 at 310N / 310N 04/15 193749

Perfect fit, no adjustments required.

For our replacement Mohair hood the extra lift means that the hood assembly in the down position is just beginning to lift so if you don't use the retaining straps then you have ensure it is well pushed down to begin with and then drop the hood lid cover from a slightly higher height to get it to latch down correctly.

For what looks like a simple part, there can be a lot of variables.
Overall length is important, but so is the relationship between rod and chamber lengths.
diameter differences between rod and chamber will also affect how they work.

They are a simple device. Basically a chamber filled with high pressure gas. As the rod is pushed in, it takes up space, so the gas is further compressed. There's nothing else inside.
If the overall length is different, this may cause problems. Too short and it will actually try to prevent full travel of whatever it is attached to, in this case the hood, in others a tailgate, etc. Too long, and it will be applying pressure which may put a strain on something.
The gas pressure will also affect its performance. Higher pressure will aid lifting the hood, but also resist putting it down. It may also put extra strain on pivots.
If the difference between rod diameter and chamber inside diameter is different, the pressure rise as it is compressed will differ from standard. This may help, or not.

Choosing replacements as close as possible to original is always the best bet.