srbliss

I put this question in the general section and not much response so I am no putting it here.

I am in the planning phase of a swap and have been thinking/planning the exhaust system. Engine will be a 5.3 (with a 5mt if that matters) with a mild cam and LS6 intake plus vette exhaust manifolds. I was originally planning on 2-1/2" headpipes merging into a single 3" cat leading to a 3" inlet and dual 2-1/4" outlets center muffler leading to a pair of rear mufflers and tailpipes. Now after staring at the bottom of the car I realize I can go dual exhaust all the way. Question is - is it worth the extra trouble to do this? The single exhaust will be a bit easier and cheaper than the duals. The car is a sleeper so stealth is more important than getting every last Hp out it. What do you think?
BTW - the car is a near mint condition 1980 white 4 door Volvo 240.

boostnut

iTrader: (7)

I would be concerned about running a single 3" cat, it may be a considerable restriction. Have you considered running dual 2.5" cats into a "Y" followed up with your previously mentioned muffler configuration?

hookemdevils22

iTrader: (12)

Here's a guideline I found. Looks like you should be about good for your power level. Well... other than the cat. I believe even aftermarket 3" cats only flow something like 5-600cfm, which isn't nearly enough for even 300 hp. You should probably do like boost said and Y into 2 cats and back if you want to keep the single exhaust setup. Or put two cats after the muffler and take it through emissions only after driving around for a while to ensure they are properly heated up.

srbliss

Thanks for the info, I know I have at least one of Vizards books. Yes I can easily do dual cats (I think) before merging into one 3" or I can go proper dual with an h-pipe, I don't think I can swing and x-pipe on this car but I won't know for sure until everything is in the car. The main goal is to keep it quiet. I live in California but I have a house in a 'non-smog' area so I don't have to worry about smog testing

hookemdevils22

iTrader: (12)

oh. In that case, get a single 3" cat and gut the damn thing.

srbliss

Just because I don't have to pass the test I can't go around smelling like raw fuel because some do gooder will turn me in as a gross polluter. While I have an address in a non smog area I live in the car hating Prius worshiping SF bay area.
I can't wait to move to the other house.