Hurricane 4:1 haven't been available for years. The 4:2:1 systems were around until a few years ago.
Although..You might find a set or 2 kicking around some random exhaust shop (if your lucky), but will spend FOREVER trying to find them! I did, and failed.
The only ones still in production (to my knowledge - did my homework as spent the better part of 10grand on a 3k) are supplied by GENIE HEADERS in QLD, under the name "Wildcat" They are a 4:1 extractor, BUT are not are "tuned" length set, as all the pipes are of different lengths. This being the only seemingly available option to me, has sent me in the direction of custom tuned 4:1 extractors for my application!
However, if its a stock application (no internals ie cam, bore, headwork ect) and all looking for is a bit more outta your 4k, then a mild carbie mod ie: downjetted 32/36 weber and a 4:2:1 set of extractors is what your looking for, as the stock cams are very low rev'n (like 4500rpm flat strappin).
If you have however gone REDICULOUSLY overboard / to town on your block like me and wanna rev to 9grand all day every day then 4:1 are the business, but as I mentioned tuned length is the only way to go!!!
Suggestion: Call head office of GENIE in QLD, and have a talk. The main guy there (who's name eludes me sorry) offered to make me customer tuned length 4:1 for $600!
Almost every other person I've spoken to has quoted around $1500+.
But yea... Hope this is of help!
ROCK ON & ROLLA FOREVER!!!
