I have a Steel OMS 121... I think its considered pretty big as tanks go. But your 131 WONT kill you. Just do all your weight checks and all that fun stuff before you go for a real dive. Do as much research and so on with the shifting of the weight aspect with your new tank and how PSI is equiv to whats really left in your tank as far as LP tanks are much different to the AL80. You can dive anything as long as your knowledgeable about the equipment. Yes it will be heavy, yes your bottom time will be longer! But one thing I like to think of is this, Safety. Your buddy will probably have an AL 80, it is 70 some cbft of air. You will have 130..... you'll have an extra 50 if he runs out, or you get in trouble. So, if you go straight to the bottom or your buddy runs out, you'll have plenty to spare, or plenty to get your butt off the bottom and try it agian!!!!!! Like many others have stressed, DO SOME POOL TIME FIRST!!