I didn't say replace your battery; I said: Anyways, if you get yourself a decent main battery under the bonnet with a secondary (or even tertiary) battery in the boot, run some good 0 gauge cable (more than one would be even better) to the boot, and do the 'Big 3', you should be fine to run a few thousand watts RMS. If you really think that just simply leaving everything as it is and upgrading just your alternator is going to fix your problems, then you are going to have to find someone who can re-wind you current one (or a spare). There are currently no high output alternators that are sold as they are to bolt directly up to the 2GR-FE. Part of Big-3 is to change Alternator isn't? I have upgrade the Power cable to 0 gauge, replaced Factory Batt and Already installed a Secondary Batt, But it seems don't really last that long, especially Staying at 13.8V or above. Don't really understand why... That's why i am looking at replacing the Alternator now... to see if that can make it staying at 14.4v...