Hello everyone!

I purchased my 2004 XJR back in may and noticed quickly that there is a severe lack of aftermarket support for these cars.

I was going to source an RR upper intake and one of the usual choices for a J-Pipe intake on the market, but figured I could probably make something just as good if not better for the same price.

Thus I created this... I need to make another trip to the dyno to test the 3.5” J-Pipe, but just replacing the upper plenum with a 3.5” tubular piece gained 12hp and 10tq at peak rpm and 18hp/20tq in the mid range! So unlike the RR upper which seems to make gains in the mid range and nothing at peak rpm, I believe I created something that can be a solid alternative to the RR upper/3” J-Pipe intake combo.

using a 3” J-Pipe like the typical intakes on the market, the stock plenum made 336hp and 358tq. With my tubular plenum we made 348hp and 368tq. The whole 3.5” combo should liven that up a few ponies.

I’ll have more numbers once I fix this failed air strut and get it back on the rollers.