- Larger/longer pump cone.
- Smaller diameter reduction nozzle (if you're currently using a stock/unmodified reduction nozzle you probably wont be able to go any smaller).
- Move the impeller closer to the leading edges of the stator vanes of the pump housing. Try removing the stock impeller spacer first. Shim out if necessary with index washers or just use the 0.5mm thick thrust washers that Yamaha uses on each side of the top end bearing in all 701's. If you want to set the impeller further back, you will have to have the hub of the impeller machined.
- Repitch the impeller (if you send the impeller out to be re-pitched, this would also be a good time to have the hub of the impeller set-back).