Thanks mate. Yeah when it comes to messing up ones lower back, I'm king there! Haha.
Another technique I like is to warm up bench on an angle just higher than 45 degrees (as much more than that it's too much front delts working) and then it a working set to failure of say 10-12 reps. Once you've racked the weight you get off and lower the bench by one notch and then go again, you may squeeze out a few reps. Keep repeating until you are at the lowest setting you can do on that bench, should be in the decline setting. The theory is that we are stronger the lower the level of the bench since the arms have a shorter distance to move, culminating in that final set on a decline. This really fries your pecs. If you struggle to squeeze out more than a couple of reps on each drop, which is ok btw, then feel free to do a very small drop of the weight but you shouldn't need more than a 2.5kg total drop in weight really given the lower angle. The ideal scenario is having 2-3 guys available during this exercises so you can just sit up each time they drop the bench +/- weight, but even alone it can be done and although it's not going to be as high intensity that way.
This whole thing can be done in reverse with dropping the weight as you raise the angle. Either way you'll fry your pecs in one giant set. If you're really crazy you can do 2-3 sets of this but if you are someone that is able to push out every last ounce from every rep and know how to contract your pecs at the top of the movement, whilst keeping your should stuck to the bench with a conscious effort, one set can be enough to stimulate growth.
Another thing I like to do that's a little different is giant sets for arms and by that I mean you warm up a biceps exercise then warm up a triceps exercise and then go for a max to failure on each and then drop the weight a little and repeat maybe 3-4 times and your arms will be blown up like never before. E.g. warm up biceps curl and skull crushers. then do a set of curls to failure and immediately do skull-crushers to failure. Drop the weight on both and get right back in. And repeat a few runs. The theory here is that your biceps gets a rest whilst triceps are working and vice versa. Additionally one is being stretched whilst the other is working since they are antagonistic muscles, potentially reducing the lactic acid build-up and re-oxygenating them. On top of that, the extra blood that floods the arms potentially creates a larger fish-tank i.e. the bigger the fish-tank, the larger the fish can grow. Although that's debatable, it's still a nice thought. Right? Lol.