If the wiring is upgraded then you could go with a higher amp alternator, but if the wiring is not upgraded, and you do not have any capacitors I'd start there first before upgrading the alternator, I had an above average system and I ran a 10 farad capacitor.
Around 1 farad per 500W of RMS power would make a big difference.
If you have done everything else already then there are some CS144 200 A Dual Rectifier alternators, also 250, and 350A ones available, but they are $$$
Here is the 200A one.
CS144 Series Self Exciting (One-Wire) 200 Amp Extreme Duty Dual Rectifier Alternator