What is the biggest Y-Pipe that I can run using with Maximum Clearance. I need a Custom Y-Pipe made, however I dont want the car scraping the ground going over road bumbs. So please help me find the biggest Y-pipe with Maximum Clearance and Good performance. I have yet to find a Mandrel bent shop that can make the Y-Pipe. What im trying to do is get some 3" Collectors and get a 3" or 2-1/2 Y-Pipe. It will flow to a 3" Hooker Catback System. I know I can go through the 1 5/8 headers to
2-1/2 Y-Pipe then back into the 3" Catback. Doing this how much back pressure will I have or will that restrict my flow. I will be running a SBC 406 w/ AFR heads, and between 450-500hp/tq

 

The Hooker 2055 y-pipe has 2-1/2" downpipes, joining in a 3" pipe at the cat. So, that shouldn't be a problem.

I'm more concerned about your 1-5/8" primaries. For a 400, that's torque motor size, not HP (probably limited to less than 5500 RPM). I know your only 1-3/4" choice in shorties is SLP, and they're expensive. But, we all know the cost of speed is exponential, not linear...

 

As the old saying goes... "Speed costs money. How fast do you want to go?"

 

Just remember that you can go out and buy all the expensive parts you have dream about, however if the parts does not have a Good combination you will have no speed and alot of money spend. backwards planning. I'm building my engine to operate under 5500 and low end torque, so 1 3/4 headers would not do any good. Also by using bigger headers you lose low end torque and gain horsepower up top. I dont want to lose low end torque remember one thing:
TORQUE WINS RACES
HORSEPOWER- IS SOMETHING YOU BRAGG TO YOUR FRIENDS ABOUT.

 

SLP recommends their 1-3/4" for a 350 TPI over 1-5/8".

A 400 is going to pump a lot more air than a 350 or 305. The larger bore and longer stroke will without doubt make torque. I think you're over-compensating for the low end. SLP 1-3/4" primaries, dual cats - that would be a good combo for a 400, even with a 5500 RPM-limited powerline.

I'm not sure where that little quote of yours came from (see it a lot), but it's bogus. Torque is work (force times distance), power is work over time. Since races are based on time, the greatest amount of work you do in the least amount of time (assuming equal weight and ability to put the power to the ground) wins races. That's horsepower.