Hi Jeff - sure you can. It is quite common for folks to swap out components for higher quality units to improve sound; not only on kits but on manufactured gear also. Some of the things you could look into is swapping coupling capacitors for better ones, signal path resistors for better ones and rectify diodes for ultra fast/soft recovery types.
Make sure you keep the values the same and do not go lower on the voltage /wattage rating than the component you swap out.
Regards
Paul
Make sure you keep the values the same and do not go lower on the voltage /wattage rating than the component you swap out.
Regards
Paul