important exhaust sound

[car10002]

hi

someone has a eb s pack with a standard 4 litre engine with extractors that go half way down the engine such as these http://members.dodo.net.au/~cason2/lukey.jpg

and a redback 2.5 inch exhaust with front and back mufflers such as this http://www.performanceexhaust.com.au...20HS1005_1.jpg

but using the standard ford cat converter

have a ef fairmont with a 4 litre engine with the exact above but a high flow cat and want to make it sound as deep as that eb does with the exact same extractors and exhaust

the note on the eb is deeper than the ef with the same exhaust and extractors for some reason. the ef has had a xr6 ecu in and does go quite good with it

would the cat converters have anything to do or what else could it be

both eb and ef have the exact brand exhausts and extractors both models with front and back mufflers