So I freshened up my L98 that had a blown head gasket while I'm waiting for parts on my LS3 Stroker (Callies Rods and Wiseco custom pistons are months out). This car ran a 13.7 1/4 mile when it was stock with some flowmaster cat back exhaust, Higher stall converter and some light external mods. I had a Procharger on it (P600B) but have since sold it years ago. (In which is ran high 12's with major traction issues)

So now, the difference between the 13.7 ET and now: the L98 has a bigger cam (cant remember the specs but I think it was .500/.510 lift, 210/220 @.050 duration and 114 LSA maybe?) and I had the L98 heads redone (milled .010" and new guides and seats. No porting), and SLP shorty headers. I had to cut off the flowmaster exhaust and tossed it in the metal recycling bin. The exhaust exits right where the cats would be. Ofc its super loud, (almost obnoxious when cruising) but I just used a Dragy device and clocked a 16.09 ET in the 1/4 mile.

I remember this thing had no power with open pipes before (I ran it open a few times 20 years ago) but never thought the lack of backpressure (or no exhaust scavenging... whatever) would kill the power down to lower than what my 1992 Convertible 305 TBI car had with an L98 cam installed. (I'm running 8 deg BTDC base timing by the way)

Anyone else experience this? I didn't want to have to spring for a new exhaust on the L98 when I have to get a new one again for the LS3 but I might have to as I can't stand it being so slow.