I've installed $70-100 eBay manifolds with accordion expansion tubes (on #1 & #6
downpipes) on both on my '96, and '98 XJs with no problem(s). Both bolted right in
and hooked up to the stock exhaust pipe. I didn't have any issues with flange thickness
as many others have. Just lucky, I suppose.
I did take a Dremel grinder to the flanges on both manifolds in order to eliminate any
sharp unfinished edges, but this was something extra that I did, and is not critical to
installing the manifold.
I replaced the zinc-plated collector bolts that came with the manifold(s) with stainless
steel bolts, and I smeared anti-seize on all of the threaded fasteners. The engine
mounts on both of my cars were fresh, stock replacements (only a couple of months
old). I also used Fel-Pro gaskets instead of the cheapo gasket that came with the
manifold(s) as they were smashed and bent during shipping.
Having a 14mm flex-head GearWrench (or equivalent) is a godsend for this task.
Be sure to re-torque the bolts after 2-3 weeks of daily driving.
That was 3, and 4, years ago and they're both holding up just fine.
Don't be tempted to get one of those APN style headers (or copy) as you'll have to grind
the bottoms of the #1 & #6 intake manifold runners to clear it (on '99-01 models, as
they have the "horseshoe" type intake manifold). Even if you manage to get it installed,
you'll end up with very hot #1 & #6 exhaust tubes being mere fractions of an inch near
to the #1 & #6 intake manifold runners.
