sorry but thats complete shisen. no exhaust system is that ineffective that by increasing the density of the forumula in the "bang", the resulting by-products (emmisions) will cause a reduction in power.

not by the amounts we are refering to here anyway. stick a great big turbo on then yes, but add say even throttle bodies will not result in a reduction in power due to excessive back pressures. in will not operate as effeiciently but it will work.