dont want a grapefruit shooter, but would like something that gives good gains. anything fitting this description under 4bills?

 

I'm not trying to be a smartass, but if you want cheap and stealth...

OEM

You can buy other systems that are shinier, lighter, louder, JDMier, etc., but nothing is going to give you "good gains" (I assume you're talking about HP) by itself.

 

can i attach a custom 2.5 mandrel bent piping to stock exhaust?

 

personally.. i would just remove the cat and cut of the bottleneck just after the cat on the b pipe and run that.. it shuld be more than enuff to help.

 

There is one more right by the muffler.

I would probably just replace the muffler as well. That and the cat are the two
major restrictions.