[SV6000]

Hey mate glad to see that everything worked out. A bad connection will cause heat to build up as it greatly increases the resistance. You will need to solder that connection again. In my race truck i directly soldered the motor to the ESC. When i first ran mine with that ESC i thought it was slow as well. It wouldnt wheelie either. It turned out that the batteries were a bit low. Sometimes the need to be ran and charged a few times before they will accept a full charge and discharge. Because of this i am switching to all flightpower packs. I run a flightpower pack in my truggy and it is quick. Even with low gearing, especially down the straight. You could also check the timing setting and frequency settings on the controller. Another thing i noticed is that you do not run any fans. My race truck speedy i ordered with active fan cooling (bigger heatsinks and a 30x30x12 fan each side) On my G3R i copied your speedy mount and bought two fans to mount on it. I had to cut a hole in a piece of aluminium to mount the bottom fan to it. Or you could run your setup on 6s. Another thing you could do is install a "black box" (available from rc-monster.com and is made by MGM just for the Zseries controllers). they are a really good tool for monitoring and recording things like temps, amp, voltage and servo position.That way you can see if the heat issue is due to a large Amp draw or another issue. But considering the size of the motor you are running...
4500(watts)/14.8V= 304.05A 4500/18.5=243.2A 4500/22.2=202. I think that is how you work it out. so as you can see 6s could be a good thing if you can drop down the size of your pinion, 2200x22.2=48840