Grounding and Power cable for my amplifier. If you see my engine bay in real life, you will get shock. Had many cable. Haha.
this one will shock u even more...
err...you should leave the holes in the beams open
those holes are there for ventilation
if water gets in and all is closed (and it will get in...thats y the whole car can drain...all the beams...under the car...the channels forming the door sill...in the bonnet...even the doors have drainage holes....), water vapor will be trapped inside n cant dry out that fast
and as im sure u all know...water n iron dont exactly make a good team
the engine will most prolly be more silent compared to using the triangular pieces
but then the life of the metal will be compromised

and btw...its not sound waves we are trying to stop from getting out when we install this sound insulation as we call it
it is actually damping material
we are basically trying to dampen the vibration of the metal surface in question
not stop sound waves from penetrating it (which is impossible as the metal is a solid and sound waves are merely vibrating air particles)
and as we were talking about water in the bonnet justnow...doors were also mentioned
if you are not aware of just how much water comes into the door during a heavy rain,...try taking off the plastic shell door cover and leave the plastic sheet on...
then get sum1 to hose the window down at full flow
(this is only a fraction of what nature can throw at your car mind you)
and then see how much water actually flows through your door
insuflex is a rubber material (granted it is synthetic)
and i am also aware that it is a closed cell system (meaning its not a sponge)
but try dipping it in water for a few minutes then take it out
all of the surface cells (which are open on the surface) will be holding water
also, when you stick it to your door,...the inside is going to be oily as there is antirust grease which they have sprayed on the inside of the door
yes, i know it can be cleaned off
but it will never be 100% oil free unless you use petrol (which you should never do as it will damage the paint...)
so the glue u are using to glue the insuflex into place will leave cavities here n there...
i understand that you will try your very best to get it to stick all over
but it can never be a 100% job
these cavities will in turn retain water when it rains and draining will be much slower
and as mentioned above, water n metal dont make good friends
also, the insuflex will accumulate ALOT of dirt over time as the surface is not smooth
presence of dirt also accelerates the degradation of metal very significantly
that is why tar sheets are always used when it comes to areas that are exposed to water
tar is a petroleum based material and thus will not be adversely affected in any significant way by the oil film left by the antirust coating which you have cleaned off
therefore, i strongly advise against the use of insuflex/superlon to insulate inside the door cavity
sifoo really sifoo...