4 branch exhaust manifold or gsi twin downpipe?

[NovaBoi92]

Just wanted to do a little upgrade to my 1.2 - better exhaust system. What would give the most performance increase, the gsi manifold and downpipe or the 4 branch? going to be used with the rest of the gsi system obviously, thanks

[mowgli]

it won't gain you very much, maybe a couple of hp, but the gsi system looks better.. the back box is identical to the 1.2 apart from the snazzy tailpipe.
the 4-1 will probably lose you power if the engine is not modified.

the 1.2 carb & the 1.3/1.4 use the same system, but the 1.3/1.4 have a 4-2 manifold then a 2-1 downpipe. it will gain a couple of hp on the std 4-1.

[NovaBoi92]

thanyou mate

[swedge]

i has a gsi downpipe thing aswell so pointless getting a 4-2-1?

[mowgli]

the 4-2-1 will flow quite well on a std-ish engine up to 120hp, and if you look up where the 2 meets the 1, you will see some crappy bent pipe bits that wouldn't hurt having a dremel shoved up them to help it out.

the 4-1 is more for a high revving big cam sort of an engine