Using HTTP Module to Change Response

Is it possible to use an HTTP Module to change the source code of a
page?

In the source code for a particular ASPX file there are many
references to the same .Css file which I have been asked to remove
from the body and place once in the header of the file in order to
improve the performance.

Here is an example of the code for what I'd like to do:

Imports System.Web

Public Class MyModule
Implements IHttpModule

Public Sub Dispose() Implements System.Web.IHttpModule.Dispose
End Sub

Public Sub Init(ByVal application As HttpApplication) Implements
IHttpModule.Init
AddHandler application.EndRequest, AddressOf
Me.Application_EndRequest
End Sub

Private Sub Application_EndRequest(ByVal source As Object, ByVal e
As EventArgs)

Dim application As HttpApplication = DirectCast(source,
HttpApplication)
Dim context As HttpContext = application.Context

Dim OriginalResponse As String = application.?????? 'Need to
extract HTML code behind page somehow!!!

If OriginalResponse.Contains("