I wasn't trying to bash on your work so my apologies if it came across that way, really my point is if your going to spend $50 on tar why not wait a month & spend $90 on roll on bedliner?

I understand working on a budget, been doing it all my life. Doing something with the wrong product to just save a buck IMHO is always the wrong way - thats just me, I'd rather wait till I can afford the proper product then use a sub par substitute which I'll likely regret. Theres also foil faced & non faced bitumen membranes available from roofing supply companies, there made by Grace & GAF, they're also peel & stick, matter of fact I have a box of it from a job & I considered using it in the coupe but decided to try the stuff formulated for sound & heat - in the end I dont think there's much difference other then the mil thickness, the rumble mat was quite thicker & I dont know if the grace stuff I have has asphalt based material in it, I wanted all rubber.

I think I bought the 24" wide x 50' roll for about $60 US awhile back - much cheaper, roll on bedliners are pretty reasonable but some are asphalt based. Herculiner, Rhino liner & a ton of other brands are available & rollers are cheap.

The next car I do that needs a repaint I'll spray bedliner instead of even using peel & stick membrane.