i would go with 2.5" duals with a x or h pipe its not going to kill the 3-5 performance (mainly because 305 and performance dont really mix) but if you ever decide to upgrade engines you will be able to support well over 400 with that setup.
Stock 305, thoughts on 3” tubing?
- Thread starter JRLeadfoot
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Depends on which 305 and what other mods have been done. An HO 305 has 2.25 exhaust and might see a couple more HP with a 2.5 exhaust. If the HO 305 has cam, intake, or header upgrades then a 2.5 exhaust would have a little more benefit. But on a typical stock LG4 305, there won't be much benefit with a 2.5 yet alone a 3 inch exhaust.
Even an ho 305, still has ridiculous low hp, that unless for sound or if someone decides to add an power adder exhaust isnt going to change anything that you will notice. assuming asking about the exhaust i feel future upgrades are probably going to happen with his build
190 hp is decent power for an 80's car and with the 9.5 CR they respond better to improvements than most 305s. The stock exhaust manifolds and LG4 cat converters are bigger restrictions to HP than the exhaust pipe sizing.
Main point is that because 305s are smaller than 350s, they don't need big pipes. Headers and a L69 cat converter would be better exhaust upgrades than bigger pipes.
Main point is that because 305s are smaller than 350s, they don't need big pipes. Headers and a L69 cat converter would be better exhaust upgrades than bigger pipes.
Due to $ constraints I used the stock single 2.25" pipe removed the cat and into a 3" in 2.5" outs single to dual outs with a Series 40 Flow Master.Sounds way bigger than a 305. Likely not any gains, I know its not the right way to do duals but did not want to change too much from stock.I am a bit of a purist.
I would use a 2 1/4 true dual exhaust with a "x" pipe and or cross over pipe .With a decent set of mufflers . High flow cats are an option depending on the state,
I had an early 80’s monte years ago. I ran the y pipe straight to a cherry bomb, with no cat. It dumped at the rear, and everyone thought I had something crazy under the hood. The car sounded so good it was embarrassing to say what was really under the hood.
That's no different than these kids today with loud turbo blow off valves on (fill in the blank commuter car) that happens to have a turbo 4 because everything does now. But a V8, especially a small black chevy has a real sound to it.
I had a Jetta with a 1.8L turbo 4 in it. With a chip upgrade it went from 150 to 200 hp in an afternoon. That car was pretty fun to drive. A bigger turbo and down pipe were on the agenda, but I traded it in for my pickup.
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