Hello hello. So i have a '90 formula 305 TPI that im going to be "Improving" slowly over the year and i want to start with the exhaust. Currently it has the stock manifolds, but the Cat and the Resonator have both been deleted and straight piped to the rear, where it has a single entry (passanger side) magnaflow muffler that leads to dual exit out one side (driver side if it matters). I want to replace these god awful log headers for some hooker equal length headers, however im running into a bit of a snag trying to determine which would be appropriate.

My plans are to do a mild camshaft down the road with new heads, just to get a basis of where its going. (Yes i know building a 305 is worse then building a 350, but it came factory with one so i want to keep it). Im currently stuck between keeping the exhaust diameter 2.5'', or upgrading to 3'' Exhaust headers. (collector size). Ideally i'd like to do 3'' but my research is showing it might not be suitable, aswell as requiring a new Y-pipe that has a 3'' in both the inlet and outlet, which is proving very difficult to find. Im not opposed to replacing the exhaust Y-pipe and back with 3'' and a new muffler (I prefer quad exit to be honest). I'd like to get some opinions and possibly even some advice on how to proceed. The car already sounds nice, im doing it mostly for a small power gain aswell as removing the restrictive stock headers and saving my starter from being smoked.

 

Go 3". Unfortunately many kits that had the appropriate sized Y-Pipes are no longer available. One option is the hooker blackheart true dual system. Its a dual 2.5" system that would be perfect for anything you get out of your 305. It has a higher cost of entry, but if you consider the cost required for a custom y-pipe, it pays for itself.

 

2.5 collectors are good, bring them to a 3" merger and 3" the rest of the way back

 

Im assuming by this you mean go with the 2.5'' headers into a Y-pipe that has a 2.5'' connector to the headers that merge into a 3'' exhaust that goes the rest of the way to the tailpipe. I did find a few Y-pipes that do just that, 2.5'' to 3''. im not planning on making crazy power so this is most likely the route i will go. the hooker Blackheart system ShiftyCapone suggested is nice however its a little bit over what id ideally like to spent on just the exhaust. Thanks!

 

My hooker headers merged at 2.5 so we cut and welded in a piece that merged the 2.5 in into a 3in. I think Flow Master actually made this merger we put in place. Then a 4th gen 3in Flowmaster exhaust the rest of the way. Only had to change a hanger or two. Direct fit. These cars need a 3in exhaust in my opinion being it's single exgaust setup really.

 

Have to agree on the Blackheart. Really surprising nobody came up with a aftermarket dual setup. If I was gonna get rid of my SLP 2otL setup, I'd go Blackheart.

Though I do say that Willie's (old member on here) dual exhaust was awesome for the shear packaging involved.