And why is that

 

The volume demands that 3 additional cylinders require, I would imagine. The flexfuel pumps flow a little better due to the nature of volume required in E85 applications. Generally, if you're going for 450 whp+ you're going to need to upgrade the fuel pump.

 

Your pump wont flow enough. Spend the $100 on a Walbro 450.

 

Another question what if i use both fuel pumps as in the colorados as a feed and the walbro 450

 

For what reason? Just swap the 450 in and be done, it can support something like 750whp on pump gas and 600whp on e85 by itself. No need to complicate things even more IMO.

 

Oh just for a simple install but yah i wont be needing both ima need to fabricate another feed line