When I first got the car I used to hear a sloshing sound behind the seats after washing. I cleaned out the drains, which didn't have much debris and flowed freely. Now, after washing the car and while drying it, I open the convertible top and stop at the midway point, then after a couple of minutes almost to the end.

What I have seen is a lot of water draining from the right drain under the door, but very little from the left drain during this procedure. Kind of like wringing out a wet towel. This has eliminated the sloshing sound, which I assumed was retained water from the wash.

Does anyone get more drainage from the right as opposed to the left? There must be a slope to the right if both drains are clear.

 

It appears the best method is to spray water repellent on your roof to avoid water from getting in there right ?

 

That helps reduce water ingress, but it doesn't prevent it.

 

I really think these are separate issues. Treating the top is necessary to protect it and extend its life but the issue here is not a leaking top. Water running off the top flows into the top “well” on each side and drains through the drain holes. It is when those drain holes get clogged with debris that problems occur.