How did you measure the performance?  Can you try using 
http://www.webpagetest.org with 10 iterations and post the webpagetest link?

I have done the testing using HttpWatch that gives you the performance 
waterfall charts.

Mod_Off
https://www.dropbox.com/sh/v4vacugv3to0rsm/rAs8g0ibQq/IEModPage_Off_HttpWatch

Mod_On
https://www.dropbox.com/sh/v4vacugv3to0rsm/C7K08KIrNw/IEModPage_On_HttpWatch

you can open the corresponding .hwl files using HttpWatch 

I don't know much about HttpWatch.  All I see are PNGs.  But it looks like the 
waterfall with MPS on isn't actually doing any rewriting.  Looks like you 
should probably authorize *.intuitcdn.net.

Can you describe in more detail how the tests were run?

Let me give you a WPT scenario.  You'd select where you want to measure the 
speed from; there are WPT servers all over the world.  They are typically in 
EC2 data centers so you can add last-mile latency selecting from a menu of DSL, 
Cable, T1, or custom latency/bandwidth/packet-loss settings.  You can then 
select a repeat count; I'd use "10", and whether or not you want to see 
repeat-view or not.

By default you'll get waterfalls for all 10 runs.  I'd throw out the first one, 
generally, when mod_pagespeed is probably just warming its internal caches if 
it's not actively running on a site.

You can also generate video, and use that to generate comparison videos like 
the ones we typically put in our blog posts, such as 
http://www.youtube.com/watch?v=8moGR2qf994

You can then share the link to the data on webpagetest.org and we can take a 
deeper look.

Feel free to ping me directly if you'd like more help.

Actually the perf environment where i set up mod_page speed is currently 
unavailable and could try sometime next week, meanwhile i did enable cdn.here 
is how the config file has been set up(masked the company information below)

    # ModPagespeedDomain
    # authorizes rewriting of JS, CSS, and Image files found in this
    # domain. By default only resources with the same origin as the
    # HTML file are rewritten. For example:
    #
     ModPagespeedDomain https://xyz-xyz.xyzcdn.net
     ModPagespeedMapOriginDomain localhost https://xyz-xyz.xyzcdn.net

Can i contact you directly, what is your email id?

Thanks,
Vikas