Hello im new here .. and i was wondering if anyone could help me out a lil bit .. first of all i have a 1991 firebird formula with the 305 v-8 ... it has the one muffler as ya'll may know .. but recently i was talked into getting the true duel flowmaster exaust .. i havn't gotten it yet but was wondering if it produces more hp then just a sinlge flowmaster .. and also does it make it louder .. the key sound im looking for is a loud rummbling like a suped up mustang gt or cobra .. i have already got my cats cut off which does make it sound better .. please help me out .. I am much grateful thanx alot

 

First off, on your stock motor you don't need dual exhaust. Now, if you plan for an engine swap down the line and are making a good amt of HP then yes true duals are worth it, but a little harder to install.

Second, you won't sound like a Mustang, they have their own sound partly due to firing order.
If you want a loud rumble at idle I'd say get the Flowmaster cat-back, however if you want a nice idle sound and loud WOT, I'd get Hooker , sound clip in the sig.

 

Thanx alot man .. also i was wondering .. how much did the 1991 305 firebird formula come stock with as far as HP .. also around how much HP did i gain by getting my cats cut off and getting the K&N air filter

 

There's a great tech data section on the homepage of this site. I believe the L03 tbi came with 170 hp.

I'd say you may have picked up about 5-7hp with gutting and the K&N, as an estimate.

 

170 hp if it's a tbi
205 hp if it's a tpi with single cat
230 hp it it's a tpi with dual cats

 

Welcome to the board, the first thing I would look into is getting headders and a y pipe. Then go with a cat back.

When you have a question and want to post a new thread, try starting out with a search, and as far as hp and tq go, look around on the first page. Down the left hand side there are a lot of good links that can help alot.