get a hold of this guy;
http://www.doverpoweronlinestore.com/index.html
he used to sell mats for 12.00 a pc at the kart racing flea markets i attend.there nice about 1 inch thick,4ft by 4ft square. shipping could be pricy though.
gm uses locktite on almost all bolts;intake,motor mounts,i think even bell housing,water pump,ect. you get the point.
i always break the bolts loose with a ratchet then off with a air gun,3/8.
seems like every time i get out the impact some bolt breaks then its time for more of a challenge...