Straight Mac 2 to1??

[D-stoorm]

I just put the mac 2 to1 system on my 80' 400 and just straight piped it sounds exactly how I want it; loud enough to piss the neighbors off down the street! But anyways with the pipes and a short angled tip it runs good w/ no backfire and what not but I did notice the significant change in power without the muffler that came with.

So I guess what I'm asking is what is the best way to improve performance while keeping it straight? Is there any packing or back pressure ideas and lastly what negative effects will this have on my engine? I will be posting pictures and video of sound, just for fun.

Anything can help!

 

[JARichmond]

A 2 in 1 will require you to rejet your carbs because it's capable of moving more exhaust out of your engine per cycle. It may not backfire, but it's sure going to be running lean. Ideally, the only negative effects you'll have are slightly lower gas mileage, but that's the price you pay for for power. If the bike continues to run lean however, you may wind up with less power than you bargained for, an overheating engine, and possibly preignition (and all the fun stuff that comes with that).
Point of the story, check out a rejetting guide. I know that someone posted a link to a good one a while back but I can't seem to find it, sorry. Hoping someone will chime in with the link I'm talking about

 

[faber]

One other thing, most of these are unpacked and have a really loud tinny / ringy sound until they are packed.

They're also generally pretty cheap as well.