Just to give some perspective, the W310 tune can be replicated if not bettered by many pro tune shops with a plastic trumpet OTR and changing the mufflers (catback), plus judicious changes to the (MAF) tune. Too easy, zero risk of claim denial if lodged with the assistance of a professional workshop.
Realistically if you throw a lifter because of a cam install, you are relying on the pro shop, throw a lifter with an OTR you will also rely on advice from pro shop to assist with your claim. But understand this is in essence a different air filter and muffler package with lots of hoo-ha and stickers thrown in, which in terms of available engineered modifications is extremely mild.
As a side note I bet my warranty on OzTrack, and post-warranty I still rely on its advice, results, and tune file updates via email are a real bonus as your needs and tune progress too. By comparison Walkinshaw is a branded corporate franchise plan leveraging the premise you pay for their insurance cover. Think if it were not a car but a baby care plan you were considering, your choice is between a home doctor on a first name basis versus a coloufully branded special offer on a flyer in the mail. If you are xenophobic and into paperwork then all you need do is read the fine print on the promo, fill your credit card details, tear out the 'gold warranty' coupon card for peace of mind and book it in. However the personal approach is more real, flexible and costs a great deal less for better results. Or at least you can haggle.
Diff'rent strokes I guess.