I have read your post and looked at the pictures. It does not say or show if you bagged through the cavity of your piece or not.
 If you want help and advice you will find it helps to be curtious.
If you did not bag through the cavity there is nothing to compress your pre-preg, holding it in place and making the resin flow.

Brian.

I did bag it and pulled the bag through the cavity. It's irrelevant though because the bag burned through in the oven and lost vacuum twice. I typed this out on the previous page. I lost vacuum twice because the bag burned through...the second time I even insulated it in wax paper and the bag still burned through.

I read that it had burned through. But you had not mentioned that the bag went through the inside as it should. You may have just bagged the outside.

Brian.

It's not surprising the bag burned through, your oven isn't really big enough for that size part and you shouldn't really rest it on a metal tray either as this may create a hot spot where it touches.

Did you post cure your mould before you put the release on for the pre preg ?

You need to burn the styrene out,if not when you cure the styrene comes out on your first cure taking your release with it

Normal household oven is ok to cure for a cure on a item like this but if you were to do another you really need a separate internal bag joined onto your outer bag rather than trying to push your outer bag down into the mould

Shouldn't you be copying the internal surface of the original manifold and not the external surface?

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