Y-Pipe
You want the best headers you can find. For an LS1 F-body, it would be QTPs or Kooks in 1 3/4" size. For a Vette, the LG Pro Long tubes reign supreme. A high velocity merge collector on the header collector is typically worth some nice gains in the mid-range and is known to squeak out a few extra ponies up high as well.
Merging the twin pipes coming off the headers is a critical item for power and sound quality. Vettes have it easy because an x-pipe easily fits and the sound quality is awesome. F-bodies are handicapped because of space constraints. For 500 rwhp, you want to run dual 3" pipes after the headers and you'll want them to merge into a 4" intermediate pipe. Anything smaller will run the risk of flow loss. Most y-pipes on the market slam the 2 pipes together like this:
When the pipes meet at close to a 90 angle, the flow is going to be lower and the sound is going to rasp and drone at 2000-2300 rpm. By using a Flowmaster merge collector or better, your sound quality will improve since the gasses meet side by side as opposed to ramming into each other. Here are a few pics of my exhaust.
Notice the dual 3" pipes merging into a 4" intermediate pipe, then a 4" cutout. After the cutout, the pipe is reduced to a 3" SLP dual dual catback. Compared to open headers with 20" extensions, my motor lost 1 hp with this y-pipe, but gained 10 rwtq in the 2500-4000 rpm range. https://ls1tech.com/forums/newreply....eply&p=7248595








