What other upgrades are available at this time?
Since the A-5 is a very "young" gun. (It started taking pre-order 4/2002). There aren't many upgrades available for it yet. So far there are Rear Velocity Adjuster (RVA), Double Trigger, Aluminum Trigger Grip, Aluminum Front Grip, Titanium Hammer, Vertical Adapter, Pro-Seal. Check
here for the complete list and reviews.
Is that a good idea to replace any internal parts?
Internal parts normally referring Hammer, Power Tube, Front Bolt. Personally I think replacing after-market internal parts brings nothing but troubles. Maybe because too many people had bad experience with them in the past. Be sure you call Tippmann before you do so.
On the other hand, the Madman Spring Kit becomes handy when you have problems with the velocity. (It can't be turned up or turned down) Check
www.maddmanproducts.com for more details.
Any "Do it yourself MOD"?
Sure, check
here . That should keep you busy for a while.
I like to make my A-5 looks like a real gun, are there any cosmetics upgrades for that?
Yes, there are many. Check
www.proteamdirect.com ,
www.extremesportsandhobbies.com ,
www.bp-usa.com for more details.
I personally have the MP-5 Ammo Clip MOD done on my A-5. You can PM me if you like to know more.