Howzit vroom

In answer to your question this morning, to make the most of your stock header get a link pipe made up (same i.d. as header) so as the combined link/header measurement is 40"then step up to the 1.75"glasspack i.d.(you won't get big gains here)

If you are in search of more power then get a 1.5" i.d. 40" long header and again step up to the 1.75" i.d. of the glasspack.

If you do the 1.5" i.d. header you will come across the major restriction in the Savage engine, the infamous exhaust port. At this stage you need to do a search,I think Lancer and Woodworker know more about the port than me.(bigger gains)

If you get a cam with say 10% more duration and you dont want to rev any harder (bad thing IMHO) then you need to extend the header by 10% too. Again speak to Lancer, he knows what grinds are available.

Clive W