3-bolt or 4-bolt exhaust housing?

[Awesome T]

I am looking to buy some ATR headers to replace cracked stockers on a stock motor. The headers will eventually find their way on to a M&A headed 274 on-center stage II. My plan was to buy 3-bolt headers, but I have a chance to buy used 4-bolt headers. My car is primarily street, and I was afraid of lag with a 4-bolt exhaust housing, but was wondering if running a 4-bolt with a small a/r, say .63, would help spoolup? Basically, would a 3-bolt with a large a/r (.82) be the same as a 4-bolt with a small a/r (.63)? Turbo now is TE-62, later will be BBT-72 or BBT-76. Converter is single-disc Vigilante 3000-3200 stall. Thanks.
PS Any downpipe alignment problems when using 3-to-4-bolt adapters?

 

[10SV6]

The 3 to 4 bolt adapter moves the turbo up and forward. It can cause some fit problems if the downpipe isn't made with it in mind.

 

[TurboTR]

On my car the .68 4 bolt hsg was a great match for a 235" GN1's engine. The .81 4 bolt was a bit large IMO for a 3000 stall converter.

TurboTR

 

[Awesome T]

Hey guys, thanks for the replies. Sounds like a 4-bolt with the smaller housing on a big engine will be good.

 

[TurboTR]

Well it depends on the stall too, but I'd guess the .81 will be good with the 274". That's what I'm starting with on mine, same converter as before with the 235" mill.

TurboTR