for a stock 305 tpi with 3" exaust and flowmaster muffler would these do anything for me (would i gain hp or what could i expect)? when i say stock, aside from the muffler and pipes i dont think anything else has been done. also i am asking about these ones beucase i may be able to get a brand new set from a private seller.
http://www.summitracing.com/parts/HED-68466/?rtype=10

is summit the best place to get these, is $430 the typical price one would pay for this setup brand new?


thanks.