So I'm good for 300-400 HP?

 

Im good for 525. booyah

 

You guys aren't understanding what this is for, but it's okay

 

my truck has 525 hp thats what your telling me i got it thankssss

 

You can always build one, - for about 12 bucks a pony, - if your conservative.

 

I really don't understand the guide at all. Why is street and race HP so different, and what engine was this based off of?

 

is the HP at the flywheel or is it RW?

 

Not based on any certain engine, - it's based on HP and what's recommended for such. Flow is different for street because it's a legal set up vs off-road. Race is built more less for WOT runs as well. For street you run converters as well.

 

So my 2.25" true duals is good up to 400 HP?

 

It's not up to. It's where your at. - Unless you got ahead of yourself, - that isn't the case, you did it right.

 

What Street numbers are for partly is,- usable Horsepower and gains across the board.

 

Ok, so if I made 400, my pipes would be adequate for it. If I go over 400, then 2.5" would be better.

 

Yes. With more HP you'll increase flow. You want what's best for scavenging.
You don't want gases dieing in your pipes disrupting velocity, - that's what happens when you go to big. To small doesn't flow enough.

If you look at the chart, you split hairs between race and street. You would have been alright going a little smaller, but you made a good choice IMO.

 

HP or TQ, it's all about what curve you want. A happy medium of coarse...