so i had just blew a header and got it re welded and i only had the headers off for a week with out useing the car and when i put headers back on and trun on the car it felt like it had no poew at all and had a weird sound to it on the exhaust also but i run real slow and shakes when i go to 1st gear what is my problem??

 

Not enough info.

What CELs are thrown? How do you "blow" a header?

 

Hey OP...periods, commas, capitals. Learn them, know them, use them.

 

I bet something else blew and the header was just an unfortunate side effect.