engine upgrade

I just bought a 1996 mustang 3.8 V6, the engine is likely junk because the previous owner blew the head gasket and drove it with coolant in the engine, it kept over heating so he put water in the radiator, then he left it to sit when the problems wouldn't go away. So a long story short, the...

i was reading a thread and i read that even after adding mods and upgrades that your car can lose hp, i was wondering how and what should i add to my 2003 mustang v6 to get more hp rather than losing it.

What are some ups and downs for installing headers? Will it change the sound of the exhaust? Which brand and material is recommended? If you know any websites that have them at a good price it would be nice if you pasted it with the reply. Thanks a lot.

Ok so I have my first mustang which is a 98 v6. The question is can I upgrade to a v8? Either the 4.6,5.0,or anything bigger (if possible). If this is possible can someone please tell me what I would need in order to make this happen and about the time frame with the right mechanic and...